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115 Cards in this Set

  • Front
  • Back
the transmission of traits from one generation to next. Also known as inheritance.
the study of heredity and variation
the genetic difference between siblings or members of same species.
DNA segments, basic units of heredity that are transmitted from one generation to next.
location of a gene on the chromosome.
asexual reproduction
single parent passes all genes to offspring. Usually just one single cell eukaryotes.
sexual reproduction
two individuals are contributing genes resulting in greater genetic variation.
life cycle
sequence of stages in its reproductive history through the course of its one generation.
the picture of its complete set of chromosomes arranged in pairs from the largest pair to the smallest.
homologous chromosomes
those that carry the genes that control the same traits;
similar in length an position of their centromere;
one is inherited from each parent.
sex chromosomes
the x and the y chromosomes that are not homologous;
not sex chromosomes;
haploid sex cells - sperm and ovum
the fusion of sperm and egg;
the process by which in the course of gamete production the chromosome number is halved so that haploids are formed.
three types of life cycles -
1. humans plus most animals
meiosis occurs in gamete production. diploid zygote divides by mitosis to produce the organism.
2. fungi, protists and some algea - after gametes fuse to form the diploid zygote meiosis occurs occurs to produce haploid cells
these then divide by mitosis to give a haploid multicellular organisms
3. in plants and some algae- alternation of generations occur, including a haploid and diploid stage, the diploid is the sporophyte, and meiosis in the diploid phase creates haploid spores which divide mitotically to produce a gametophyt, the gametophyte produces haploid gametes through mitosis and the fertilization occurs producing a diploid zygote
meiosis and mitosis
both are preceded by replication of the DNA
meiosis 1 and meiosis 2
this replication of DNA is followed by two stages of cell division
each of the chromosomes replicate resulting in two sister chromatids attached at their centromeres, the centrosomes also replicate in this phase
prophase 1
chromosomes condense homologous (consisting of two sister chromatids)pair up, synapsis occurs-joining of two pairs of homologous chromosomes along their length, newly formed structures called tetrad has four chromatids, parts of the hologous chromosomes undergo crossing over at chiasmata (places at which homologous chromosomes overlap during synapsis, centrioles move to opposite poles, nuclear envelope disinegrates, spindle microtubules attach to the kinetochores, forming on the chromosomes that begin to move to the metaphase plate of the cell
synapsis (prophase)
joining of two pairs of homologous chromosomes at their lengh
newly formed structure from synapsis has 4 chromatids.
where homologous chromosomes overlap during synapsis
3 different things that lead to variation
independant assortment, crossing over, random fertilization
independant assortment
in metaphase 1 chromosomes can pair up in any combination with any of the homologous pairs facing either pole
synapse, exchange of homologous parts of two
random fertilization
any sperm can hit egg
a heritable feature of an organism that varies among individuals
difference in a trait
pure or true breeding
all of offspring of of the same type, ex: when a pea plant is self pollinated
the crossing or mating of two true breeding different varieties of an organism
P generation (parental generation)
true breeding parents in a hybridization
F1 generation
their offspring
F2 generation
their offspring if F1 generation is crossed
4 major conclusions of mendal
1. alternative versions of genes cause variation in inherited characteristics among offspring
2. for each character every organism inherits one allele from each parent
3. if two alleles are different the dominant allele will be fully expressed in offspring, a reccessive allele will have no noticable effect
4. the two alleles for each character separate during gamete production -mendels law of segregation-
law of independant assortment
each pair of alleles will segregate independantly during gamete formation
same alleles
different alleles
phenotype versus genotype
appearance vs. genetic makeup
crossing of a recessive homozygote with an individual exibiting the dominant phenotype in order to find out if the organism is homozygous dominant or heterozygous dominant
monohybrid cross
cross involving the study of one character (flower collor)
dihybrid cross
two characteristics
dihybrid genotype
gene combination or genotype
rule of multiplicationn
when calculating the probability that two or more independant events will occur together in a specific combination, you multiply the probabilities of each of the two events
rule of addition
calculating the probability of an event that could happen any number of ways, you add the probabilities of the ways it could happeh
incomplete dominance
the F1 hybrids have an appearance that is between the two parents
complete dominance
heterozygote and homozygote for dominant allele are indistinguishable
two alleles are dominant and effect the phenotype in two different and equal ways, example is human blood type
multiple alleles
most genes exist in different forms, ex. is human blood type
ability of a gene to effect many different traits in an organism
ability of a gene at one location to alter the effects of a gene at a distant location
polygenic inheritance
two or more genes have an additive effect on a single character in the phenotype
is male square female diagram, white no trait, black trait. through the patterns they reveal pedigrees can help determine the genome of individuals and can also help predict genome of future offspring
recessively inherited dissorders
alleles that cause genetic errors either code for a dysfunctional protein or no protein at all, both must be reccessive
heterozygotes with normal phenotype have the mutant allele
cystic fibrosis
mutation in an allele that codes for a certain cell membrane protein that functions in the transport of chlorine into an out of cell, breathing problems
allele that codes for a dysfunctional enzyme that is unable to break down certain lipids in the brain
cycle cell anemia
caused by an allele that codes for a mutant hemoglobin molecule that forms long rods when the oxygen levels in the blood are low,
huntingtons disease
example of a late acting lethal allele
chromosome theory of heredity
early 1900s, stated genes have specific loci on chromosomes, it is chromosomes that segregate and assort independantly
sex-linked gene
one located on the sex chromosome, usually on the Y, fathers can only pass it on to daughters, women must be homogenous for it to take effect
non sex linked genes
linked genes
located on same chromosome inherited together during cell division, red hair and freckles, do not do independent assortment but can have recombination by crossing over, farther apart genes are from each other the greater chance of recombination
genetic recombination
production of offspring with new combination of genes inherited from parents
individuals who receive new combination of genes from parents
parental types
receive non-recombinant genes, their phenotype matches that of one of the parents
genetic map
ordered list of the genes and their loci along a particular chromosome using recombination data
linkage map
genetic map based on recombination frequencies and map units are used to express distances along the chromosome
map units
equal to a one percent recombination frequency
sex linked disorders
muscular distrophy, hemophilia, caused by absence or defection of a protein
Barr body
inactivated chromosome in women so that they have the same number of working genes as men
members of a pair of homologous chromosomes do not separate properly during meiosis one or sister chromatids dont separate properly in meiosis two as a result one gamete receives two copies of the gene while other gamete receives none
if the faulty gametes engage in fertilization the offspring will have an incorect number of chromosomes
fertilized eggs that have received three copies of the chromosome in question
fertilized egg receives just one copy of a chromosome
condition of having more than two complete sets of chromosomes somewhat common in plants
chromosome segment that has no centromere, broken off and lost during segregation, cell that receives partial chromosome will be missing that fragment
if the chromosome fragment that broke off causing the deletion above becomes attached to its sister chromatid, zygote will get a double dose of genes on that chromosome
a chromosome fragment breaking off and then reataching to its orginal position but backwards
chromosome fragment joins a non homologous chromosome, this moves a segment of one chromosome to a non homologous chromosome
genetic disorders caused by chromosomal stuff
down syndrome-aneuploidy condition of chromosome 21, trisomic for 21

-clinefelter syndrome-aneuploid condition in which a male posseses XXY

-turner syndrome- just one X chromosome, called monosomy
x-ray crystallography
process used to visualize molecules three dimensionally, refracting x ray images, DNA first visualized
double helix
twisted ladder with rigid rungs
semi conservative
at the end of its replication each of the daughter molecules has one old strand derived from the parent strand of DNA and one strand that is newly synthasized
origins of replication
sites at which the replication of DNA begins
replication bubble
initiation proteins bind to the origin of replication and separate the two strands
DNA polymerase
enzyme that catalyzes the elongation of new DNA at the replication fork
anti parrallel
strands of DNA run in the opposite direction
leading strand
DNA replication occurs continuously along this strand
lagging strand
DNA replication does not occur continually along this strand
okazaki strand
lagging strand synthesized in these separate pieces which are sealed together by DNA ligase to complete DNA strand
enzyme responsible for initiating DNA replication, joins RNA nucleotides to create a primer which is required in order for a DNA polymerase to proceed
DNA helicases
enzymes that are responsible for unwinding the DNA helix as replication proceeds
single strand binding proteins
holds the strands apart for the duration of replication
several different factors contributing to accuracy of DNA replication
1. specificity of base pairing
2. mismatch repair - special repair enzymes fix incorrectly paired nucleotides
3. nucleotide excision repair - incorrectly placed nucleotides are excised by an enzyme called nuclease, and gap is filled with the correct nucleotides
DNA polymerase can only add mucleotides to the 3' end of a molecule.- it would have no way to complete 5' end of molecule. so, linear chromosome of eukaryotes utilize this enzyme which catalyzes the ends of the molecules, called telomeres.
one gene-one polypeptide hypothesis
each gene codes for a polypeptide, which canb-or can constitute a part of - a protein
the synthesis of RNA using DNA as a template. takes place in nucleus of eukaryotic cells
Messenger RNA or mRNA,
type of RNA produced during transcription. carries genetic message of DNA to protein making machinery of the cell in cytoplasm.
synthesis of polypeptides. takes place in the cytoplasm of eukaryotic cells at ribosomes
transcription results in this,
undergoes RNA editing and processing to yield the final mRNA that participates in translation
triplet code
in DNA the instructions for building a polypeptide chain are written as a series of three nucleotide groups
template strand
in transcription only one strand of the DNA is transcribed - this is the strand...
complementary strand is mad eup of triplets called codons that are read or translated, in the 3' to 5' direction along the mRNA. Each codon specifies on of the 20 amino acids which are incorporated into a growing polypeptide strand
genetic coed is reduncant, more than one codon codes for each of the 20 amino acids.
reading frame
cotons are read based on a consistent reading frame - the groups of 3 must be read in the correct groupings in order for translation to be successful
RNA polymerase
enzume that separates the 2 DNA strands and connects teh RNA nucleotides as they base pai along the DNA template strand. (RNA polymerases can add only RNA nucleotides to teh 3' end of the strand, so RNA elongates in the 5' to 3' direction
promotoer sequence
DNA sequence at which RNA polymerase attaches
DNA sequence that signals the end of the transcripton
transcripton unit
the entire stretch of DNA that is transcribed into mRNA
three main stages of transcription
1. initiation
2. elongation
3. termination
initiation - prokaryotes
in prokaryotes a group of proteins plus RNA polymerase, bound to promoter region of a DNA sequence is collectively known as a transcription initiation comples.
initiation - eukaryotes
process is more complex, but it also involves the binding of RNA polymerase to a promoter sequence
RNA polymerase moves along the DNA, continually added to the 3' end of the growing chain. as complex moves down the DNA strand, the double ehlix reforms with the new RNA molecule straggling away from the DNA template.
occurs after RNA polymerase transcribes a terminator sequence in DNA, and the transcribed RNA sequence is the actual termination signal