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199 Cards in this Set
- Front
- Back
genome
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all the genetic information in a cell
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gene
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unit if biological information encoded in dna
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what parts of the cell carry dna
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mitochondria
chloroplasts nucleus |
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which gamete provides information for mitochondria and chloroplast development
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the egg
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chromosome
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single dna strand with proteins
long and thin until condensed in cell division |
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chromatin
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complex of dna and proteins that make up chromosomes
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diploid
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2 sets of chromosomes
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haploid
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1 set of chromosomes
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somatic cells
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diploid cells of the body
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gametes
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haploid reproductive cells
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homologous pair
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similar (near identical in physical shape and size) chromosomes
1 from mom 1 from dad |
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Are sex chromosomes homologous
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no
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autosome
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all chromosomes other than sex chromosomes which are the same from male and female
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sister chromatid(s)
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products of DNA replication
2 chromatids are produced for each chromosome (replicating each strand of DNA) They are identical |
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what are sister chromatids held by
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cohesion @ centromere
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Mitosis
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division of the nucleus
chromosome sets are conserved |
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use of mitosis
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asexual reproduction
somatic cell development and repair |
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Interphase
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preparation for mitosis
G1-gap phase 1 (enzymes and proteins) S- synthesis (DNA replication) G2- gap phase 2 (more prep) |
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Prophase
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sister chromatids connect and condense
nuceoli disappear mitotic spindle forms, extending from centrosome (made of centrioles) centrioles move towards pole |
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Prometaphase
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microtubules attach to kinetochores
nuclear envelope breaks |
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Metaphase
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spindles move to the poles
chromatids line up @ metaphase plate |
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Anaphase
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sister chromatids are separated due to the polymerization and depolymerization of microtubules
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Telophase
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formation of nuclei
spindle breaks down chromosomes decondense |
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Cytokinesis in animals
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actin filaments form cleavage furrow and pinch
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cytokinesis in plants
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cell plate is formed via vesicles
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polyploid
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more than 2 sets of chromosomes
ex: wheat is 6n and oat is 8n |
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zygote
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fertilized egg
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n
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number of unique chromosomes hat make a chromosome set
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ploidy
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number of sets (1n, 2n, etc)
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human chromosome
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46 (diploid)
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karyotype
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display of condensed chromosomes arranged in pairs (homologous chromosomes grouped)
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germ cells
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specialized cells in the ovaries and testes that will undergo meiosis to produce gametes
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why does mitosis first duplicate and then divide
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because cells that are reproduced would not be genetically similar which would lead to problems with carrying out cell function and communicating
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what happens after a sperm succeeds to enter the egg
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it changes its outer coating so that no other sperm can get in
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Prophase I
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chromosomes condense
homologs (they are previously duplicated from synthesis phase) will pair up to a tetrad, a process called synapsis (they become glued together by proteins) homologs will exchange genetic information (crossing over) which will form chiasmata nuclear envelope breaks down spindle apparatus forms |
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what is a purpose of the chiasmata
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to hold together homologs to ensure equal distrubution during metaphase I
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Metaphase I
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homologs attach to spindles and line up @ metaphase plate
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Anaphase I
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homologs are separated to poles
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Telophase I
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Cleavage furrow or cell plate develops and the nuclear envelope reforms
cytokinesis follows |
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Prophase II
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chromosomes recondense and spindle apparatus forms
*no replication occurs |
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Metaphase II
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sister chromatids (which are not identical due to crossing over) are attached to spindle apparatus and line up @ metaphase plate
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Anaphase II
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the sister chromatids are separated to opposite poles of the cells
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Telophase II
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Cleavage furrow or cell plate forms
nuceli form again cytokinesis follow to produce 4 haploid daughter cells |
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How is genetic variation maintained
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Independent assortment-you don't know where the m + d chromosomes will line up in metaphase I
crossing over- makes a new combination of alleles |
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how do you determine how many types of assortments are there
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2^n
n = number of chromosomes in a set ex: humans n = 23 |
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what was the old idea of inheritance
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the blending of traits
parental traits were blended like paint colors |
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what is the new idea of inheritance
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that we inherent packets of information- genes
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what were the 7 pea plant traits that mendel studied
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Color
Flower position Seed color Seed shape Pod Shape Pod color Stem length |
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What are 3 critical features of all the traits mendel studied
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they were true breeding
they produced fertile progeny no intermediates |
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How did mendel perform his monohybrid cross
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he cut the stamen of one pea plant and pollenated the carpel of another pea plant (pea plants are self pollinating)
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F1 generation
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offspring of monohybrid truebreeding cross
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F2 generation
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offspring of self-pollinated F1 generation
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alleles
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alternative version of a genes
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Law of Segregation
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two alleles separates during gamete formation; one to each gamete
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genotype
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genetic makeup
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phenotype
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physical makeup
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locus
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chromosome location referring to a specific gene
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testcross
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used to determine the genotype of an unknown species
unknown x true breed recessive |
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law of independent assortment
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each pair of alleles segregates independently of other allele pairs during gamete formation
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product rule for independent events
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probability of event 1 and 2
prob. 1 x prob 2 |
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mutually exclusive rule (sum)
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probabilty of event 1 or 2
prob. 1 + prob 2 |
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monohybrid
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heterozygous for one character
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dihybrid
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heterozygous for two characters
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genotypic ratio for a monohybrid cross
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1:2:1
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phenotypic ratio for a monohybrid cross
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3:1
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a homozygous genotype makes how many types of alleles
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1
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a heterozygous genotype makes how many alleles
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2
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How many different types of games can a trihybrid make? (AaBbCc)
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2 x 2 x 2 = 8 gametes
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How many different gametes can rr Aa Bb Cc Dd make?
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1 x 2 x 2 x 2 x 2 = 16 gametes
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When determining the probability of a gamete that is contains more than one gene or trait, how do you calculate it?
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take the individual probability for each allele and mutliple it
ex: what is the chance of Aa Bb Cc Dd producing an a b c d gamete? 1/2 x 1/2 x 1/2 x 1/2 = 1/16 |
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When determining the probabilty of a zygote containing more than one traits, how do you calculate it
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that the probability of the gametes that would produce that genotype
ex: In a self cross of Aa Bb Cc Dd what is the chance of producing a zygote aa bb cc dd 1/16 x 1/16 = 1/256 |
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pleiotropy
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a gene that affects multiple phenotypic traits
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epistasis
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a gene at one locus alter the phenotypic expression of a gene at a second locus
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pleiotropy
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one gene affecting multiple traits
ex: the gene that is responsible for sickle cell anemia is also responsible for things like pain, stroke, etc. |
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epistasis
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the interaction of genes that control a specific trait
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why are pedigrees important
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because people can be crossed just for the sake of genetics
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pedigree
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the genetic family tree
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carrier
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heterozygous individual that has a recessive gene that corresponds to a disorder
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square
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male
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circle
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female
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colored
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affected
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Give an example of epistasis
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In order for blue primroses to be made, they must have dominant traits that code for rose colored and mauve colored primroses
In labradors, homozygous recessive leads to a yellow dog. However homozygous dominant or heterozygous leads to a brown or black dog. However, the color of brown or black is determined by a different set of genes. Homozygous recessive is brown, and dominant is black. |
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A Corn plant is a diploid plant with n = 10. How many sister chromatids are present at
mitotic metaphase? meiotic metaphase I? meiotic metaphase II? |
n = number of homologous chromosomes in a set
diploid = 2n Therefore somatic cells contain 20 chromosomes. At mitotic metaphase synthesis has occurred, leading to double the amount of chromosomes = 40 (each chromosome has 2 chromatids) At meiotic metaphase I, the same senario as above is occuring, so 40 chromatids. At meiotic metaphase II, the homologous chromosomes have been separated, but not the chromatids, so the # divides in 1/2 to be 20 chromatids |
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3 processes unique to meosis that cause genetic variation
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Crossing over (recombination between homologous chromosomes)
Segregation of homologous chromosomes Independent assortment of nonhomologous chromosomes |
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where does the separation of sister centromeres occur?
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anaphase and anaphase II
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A cross is being made between A/A B/B C/C D/D x a/a b/b c/c d/d
a) What is the genotype of F1 b) how many different genotypes are possibly in the F2 c)what is the fractin of F2 individuals that will be phenotypically recessive for all 4 factors |
a) A/a B/b C/c D/d
b) There are 3 different genotypes A/A A/a a/a, and four different genes. 3^4 = 81 c) Figure out the probability of a homozygous recessive gene. There are 4 options and 1 is homo rec. so 1/4. Multiply it 4 times to represent the 4 genes to get 1/256. |
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What is the 5 conclusions that resulted from mendel's experiments
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1. each gene controls only 1 unique trait
2. 1 of the two alleles is dominant over the other 3. Two alleles for each gene 4. Phenotypes are not influenced by the environment 5. Each gene considered were on a different chromosome |
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What are examples that show that mendel's idea of 1 gene to one trait doesn't apply at all times
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Epistasis: two or more genes control 1 trait
Pleiotropy: 1 gene for multiple traits Polygenetic: Additive effects of 2 or more genes affect a phenotype |
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polygenetic inheritance
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additive effect of 2 or more genes affect a single phenotypic characteristic
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quantitative characters
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not an "either-or" trait because they vary so much
like height or skin color |
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Give examples that show that mendel's idea that 1 allele always dominant is not always so
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Incomplete dominance
Co-dominance |
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Incomplete dominance
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where a heterozygous intermediate results that is between the homozygous dom and rec.
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co-dominance and an example
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the two alleles both affect phenotype
ex: blood in humans AB blood type shows sugars that Ia and Ib correspond to |
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O blood type
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no sugars
Io Io |
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B blood type
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has B sugar
Ib Ib or Ib Io |
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AB blood type
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Has A and B sugars
Ia Ib |
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A blood type
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has A sugars
Ia Ia or Ia Io |
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what animal did morgan work on?
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fruit fly
drosophila |
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what was the wild type of flies in morgan's experiments
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red eyes
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what was the mutant type of flies in morgans experiments
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white eyes
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what does w w/ a + signify in morgan's experiments
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wild type
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Explain morgan's fly experiment and his hypothesis that resulted from it
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He crossed a wild type female w/ mutant male, produced all red eyed f1 kids.
He then crossed two F1 hybrids and got a result of the typical 3:1 phenotypic ratio. However, the white eyed flies were only male. He concluded that it had to be sex linked |
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Who do males receive their Y chromosome from
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dad
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who do males receive their X chromosome from
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mom
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who do females get their x chromosomes from?
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Have to have dads
and have 1 of 2 of moms |
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hemizygous
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Partially dominant
ex: X carries dom paired w/ Y |
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what is the main purpose of the Y chromosome
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sperm fertility
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SRY
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it is a gene that is responsible for the determination of sex.
The presence of it will lead to the development of testes in the gonads of a fetus |
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heterogametic
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individuals that can produce gametes that contain one of the two types of chromosomes
ex: males are heterogametic XY |
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Sex linked genes in humans
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gene physically on a sex chromosome
ex: color blind, hemophilia, muscular dystrophy girl must be homozygous boy must be hemizygous and receive it from mom |
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sex influenced
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sex hormones that affect a trait
ex: baldness |
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sex limited
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trait only found on one sex
beard, breasts, etc |
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What does a diamond mean in a pedigree
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a hypothetical child (one yet to be born)
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How do you know if a pedigree is carrying a trait that is autosomal recessive
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If it has males that are unaffected (clue that it is not sex linked)
Heterozygous carriers are unaffected |
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How do you know if a pedigree is looking at a trait that is autosomal dominant
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To see if it is not sex linked, looked to see if a particular gender is affected
Next, see if 1/2 of the children are affected |
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How do you know if a pedigree is looking at a trait that is x-linked recessive
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Depending on how the parents are affected (homozygous or heterozygous), look at which gender is affected. Typically it will be only males that are affected.
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How do you know if a pedigree is looking at a trait that is x-linked dominant
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Typically, girls will be affected.
Once again, look at the parents genotype and remember the rules of passing chromosomes Girls will always receive X from dad, boys will always receive X from mom. Girls will receive one of mom's two Xs |
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Barr Body
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an inactive X chromosome that will line the nuclear envelope.
The chromosome protein and DNA structure has been altered |
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X inactivation in females
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Females contain 2 X chromosomes, so one becomes inactive so as to not have too many genes competing.
This X inactivation is chosen at random between the two X chromosomes at embryonic development. As a result, about 1/2 of the cells in the body of a female will express one X chromosome and half will express the other X chromosome. |
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how many genes does the Y chromosome in humans have
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78
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how many genes does the X chromosomes in humans have
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11,000
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what scientist first described recomination
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TH Morgan and his experiments on fruit flies
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sex linked gene
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refers to a gene on a sex chromosome
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linked gene
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two or more genes on the same chromosome that tend to be inherited together
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Give examples of how sex is determined in other animals and how it differs from humans
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Crickets- absence of X leads to males
Birds/Chickens- females have the different chromosome (ZW) Bees-Haploid (unfertilized) = males and diploid leads to females Fish-age will determine sex (they change throughout life) Turtles-temperature that egg was growing at because the enzyme that is responsible for sex determination functions differently at temperature |
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Genes that are close together are typically inherited how
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together
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Genes that are typically father apart are inherited how
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through independent assortment
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Explain Morgan's experiments with flies and autosomal traits
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Morgan crossed a homozygous wild type fly (grey w/ normal wings) with a homozygous mutant type (black w/ small wings)
They produced dihybrid offspring that looks like the wild type parent (grey and normal wing). The dihybrid was crossed with a homozygous mutant type which lead to produce 2 children that looked like parents (wild type and mutant type) and 2 children that had altered phenotypes (1 that was grey w/ small wings and 1 that was black with normal wings) The number of offspring that didn't look like parents were smaller in number than the offspring that did look like the parents |
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genetic recombination
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the production of offspring with combinations of traits that differ from those found in either parent
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parental types
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offspring that look like parents
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recombinant types
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offspring that do not look exactly like parents
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Review Morgan's experiments with flies and X-linked traits
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It is basically the same as the autosomal traits
Make sure to do a cross to understand |
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Recombination frequency
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total # of recombinant types / total number of progeny
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According to mapping genetics, the father apart the genes, the _______ the probability that _______ will occur
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the higher the probability that crossing over will occur
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map unit
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1% recombination frequency = 1 centimorgan
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nondisjunction
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results from a spindle that doesn't funciton properly
What results is that either homologous chromosome are not probably separated in Meiosis I or the sister chromatids are not properly separated in Meiosis II |
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Aneuploidy
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an abnormal number of chromosomes
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Trisomy
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(2n +1)
When an abnormal gamete with an extra chromosome combines with a normal gamete |
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Monosomy
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(2n -1)
When an abnormal gamete without a chromosome combines with a normal gamete |
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Down Syndrome
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Trisomy 21
47 chromosomes leads to extra 21st chromosome |
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Edwards syndrome
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trisomy 18
extra 18th chromosome |
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Triple X syndrome
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trisomy of sex chromosome X in girls
XXX |
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Klinefelter syndrome
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trisomy of sex chromosome X in boys
XXY |
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Turner syndrome
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the absence of an X chromosome
X |
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Supermale syndrome
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The addition of a Y chromosome
XYY |
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Proteins are polymers of
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amino acids
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DNA is a polymer of
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nucleotides
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purines
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A and G
2 C |
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pyrimidines
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C and T
1 C |
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What were the two proofs that showed that DNA was genetic material
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DNA could "transform" bacteria
DNA was shown to be the genetic material of bacterial viruses |
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transformation
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change in genotype and phenotype due to the assimilation of external DNA into the cell
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Explain the experiments of Griffith
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Griffith did tests with a harmful and not harmful strain of bacteria in mice.
S. bacteria = virulent R. bacteria= nonvirulent Mice w/ S. bacteria = dead Mice w/ R. bacteria = live Mice w/ heat killed S. Bacteria = live Mice w/ heat killed S. Bacteria and live R. bacteria = dead The blood from the last mouse experiment was found to contain S. bacteria that was live. *concluded that there was a transforming principle |
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Explain the experiments of Avery, McCarty, and MacLeod
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They extracted protein, lipid, DNA, and carbs from S. bacteria and combined each w/ R. bacteria.
Only DNA turned the R. bacteria to S. bacteria |
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Explain the experiment of Hershey-Chase
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They wanted to see whether proteins or DNA was incorporated into the host cell of bacteriophages.
They cultured phages in S35 (radioactive) which was incorporated into the protein of the phage. The phage was then exposed to bacteria cells. The phages were then thrown off the bacteria cells in a blender. The mixture was centifuged. This process also occured with P32 being incorporated into the DNA of the phage. Basically, what was shown was that DNA was what was incorporated into the cell. |
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Structure of DNA nucleotide
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Phosphate to 5C
Deoxyribose Base to 1 C |
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5'
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Phosphate
beginning of DNA strand |
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3'
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OH
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DNA shape
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antiparallel
double R handed helix |
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bond that links DNA backbone
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phosphodiester
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Watson and Crick
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Discovered shape of DNA by compiling the ideas of many.
Chargaff: A =T and G= C Pauling: DNA has multiple strands Rosalind: x ray crystallography showed that dna was a helix that was 2 nm wide and repeated every 3.4 nm |
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DNA replication basic idea
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H bonds are broken and each strand serves as a template based upon base complimentarity
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3 models for DNA replication
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conservative: old w/ old, new w/ new
semiconservative: old/new new/old dispersive: old and new mixed |
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Meselson-Stahl experiment
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cultured bacteria in N15 and then again in N14
DNA centrifuged after 1 replication which lead to a heavy/light mixture (ruled out conservative model) 2 replications: light and heavy/light (ruled out dispersive model) |
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Does DNA replication occur at one place?
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No because it would take too long
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In what direction does DNA replication occur?
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both directions
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replication fork
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site where parental DNA is being unwound
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Helicase
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enzymes that untwist double helix at replication fork
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Single Strand binding protein
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bind to unwound DNA strands to stabilize
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Can DNA polymerase begin replication?
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No
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What initiates DNA replication?
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a RNA nucleotide chain called a primer which is synthesized by primase
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How are nucleotides added during DNA replication
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DNA polymerase will add nucleoside triphosphates that will use the energy of breaking the 3P
1 P stays and 2 leave |
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At what end, 5' or 3', does DNA elongation occur at the new strand in dna replication
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at the 3' end
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Leading strand
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DNA strand that is made beginning at its own 5' end and moves to 3' end but it will begin at the 3' of the old strand which will allow for it to be made continuously
follow replication fork |
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lagging strand
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DNA strand made beginning at it's 5' end and moves to 3' end. However, it has to be made in chunks because it is begins in the 5' end of the old strand.
It will move opposite to the replication fork. |
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How are the lagging strand fragments placed togher?
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dna polymerase I will replace rna primer w/ dna and then dna ligase will bind all the fragments together
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Telomeres
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repeated nucleotide sequences that prevent shortening of dna sequences and allow for protection.
they are done by telomerase which adds nucleotides w/ its own RNA sequence |
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Genes code for
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all proteins
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General view of DNA to proteins
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DNA ----> mRNA ---> protein
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RNA structure
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single stranded
phosphate bound to ribose bond to a base A --> U G --> C |
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Explain Transcription
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RNA polymerase will bind to a promoter in the DNA sequence which contains a TATA box and transcription factors. RNA polymerase will open the DNA stand and will bind RNA complements to DNA together. Eventually RNA poly. meets a terminator sequence in the DNA and will leave.
**RNA polymerase only opens the DNA strands locally |
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What strand is the template strand in transcription?
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3' to 5' end
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3 steps of transcription
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Initiation
Elongation Termination |
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transcription factor
|
collecitn of proteins at the promoter that will help in binding RNA polymerase
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Introns
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parts of mRNA strand that do not code for proteins
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Entrons
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parts of mRNA strand that code for proteins
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How is the mRNA strands finalized
|
The introns are spliced out
5' end gets a cap w/ a G 3' gets a poly A tail |
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Codon
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triplet of RNA bases that code for 1 of 20 amino acids
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tRNA
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transfer RNA
responsible for interpreteing mRNA to proteins |
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structure of tRNA
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they are a twisted RNA strand with an anti codon which is the compliment of its equivalent mRNA codon
binds to amino acids in the cytosol and brings them to ribosomes |
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amino actyl tRNA synthesases
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proteins that aid the addition of amino acids to tRNA
|
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Protein structure
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polar molecule
amino group NH2 at one end carboxyllic acid at the other end |
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general structure of an amino acid
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R
NH2 - C - COOH H |
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What binds amino acids together
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peptide bond
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Ribosomes
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made of large and small subunits consisting of proteins and RNA molecules called ribosomal RNA
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3 binding sites of ribosomes
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P site: where tRNA holding peptide chain sits
A site: where tRNA holding next amino acid sites E site: where tRNA exits |
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How is the peptide chain transferred in ribosomes
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with the aid of GTP for energy the peptide chain is transferred from the P site to the A site
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Explain the beginning of translation
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small unit of ribosome binds
tRNA w/ methionine binds large complex will then bind with the help of GTP |
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how does translation end
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a stop codon will bind to the A site which will cause everything to disassemble
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polyribosomes
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strings of ribosomes that are synthesizing proteins on one mRNA strand
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