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85 Cards in this Set

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what is codominant alleles
alleles that lack complete dominant and recessive relationships and are both observed phenotypically
incomplete dominance alleles
alleles that lack dominance relationships and result in heterozygotes that have intermediate phenotype that is distinct from either homozygous parent. "blend"
based n what you have learned about Down syndrome briefly explain the following observations:
a) women above the age of 35 have a higher chance of giving birth to children with Down syndrome
b) 5% of Down syndrome is heritable
a) In woman eggs are in arrested state in metaphase until ovulation starts, the later it starts the higher chance that nodisfunction occurs
b) 5% is inheritable by robersonian translocation if both parents carry the gene
Genetic code is said to be triple, degenerate, non overlapping, and universal. comma free, ordered. EXPLAIN
Triple- genetic code is composed of nucleotide triplets. Three nucleotides in mRNA specify one amino acid in the polypeptide product; thus, each codon contains three nucleotides

Nonoverlapping- Each nucleotide in mRNA belongs to just one codon except in rare case where genes overlap and nucleotide sequence is read in two different reading frames

Degenerate- All but two of the amino acids are specified by more than one codon.

Universal- With minor exceptions, the codons have the same meaning in all living organisms from viruses to humans

comma free- there are no commas or other forms of punctuation within the coding region of mRNA molecules. During translation, the codons are read consecutively
Who was credited with linking gene for eye color in Drosophila
Thomas Hunt Morgan
What is the basic chromosome number (N)
In a cross between a colorblind male and a woman with no history of colorblindness. What is the chance that any of the sons will be colorblind?
An individual with the genotype as XO is known as being female or male?
The sex determination system in chickens is
Best explanation for a XX and phenotypically male is
a small piece of y chromosome containing sRY region is inserted on X chromosome
Individual with two kinds of gametes is
Dosage compensation for x-linked genes is achieved by
inactivation of one of females x-chromosome during early developement
Why is y chromosome able to pair with x chromosome during meiosis?
The sex chromosomes provide a complication in meiosis because they are not homologous, yet they do pair up during prophase I of meiosis. The are able to pair up because they have a region called the pseudoautosomal region which is homologous between the X an Y chromosomes. The rest of the X and Y chromosomes, including the region around the centromere are not homologous.
Which study of genetics deals with the analysis of stained chromosomes
The largest and smallest chromosomes are
1 and 21
What is the term used for one that carries extra sets of chromosomes
Which implies genetic imbalance
polyploids created by hybridization between different species
polyploids created by chromosome duplication within a species are called
The under or overrepresentation of a chromosome or chromosome segment (implies genetic imbalance)
XXY - male - 2n+1
X, 45 - FEMALE
Triplication of chromosomes
Missing portion of chromosome
Segment of chromosome detach and attaches to different chromosome
what does 7p refer to?
chromosome 7 short arm
Crossing over results in
what is used to measure intensity of linkage between genes?
recombination frequency
Genes linked tightly recombine less
If two genes are not linked they ...
independently assort
Crossing over occurs in the late prophase at the time chiasmata can be viewed
Begins in early stage of prophase when it can't be viewed
Five stages of Prophase of meiosis 1
Zygonema- crossing over initiated
Pachynema- Crossing over proceeds
Diplonema- crossing over completed and becomes visible
Diakinesis- chiasmata disappears
What method is used to estimate # of crossovers?
count chiasmata and recombination chromosomes
18 out of 100 chromosomes recovered from meiosis crossover in vg and B. How far apart are they
18 centimorgans
Coefficient of coincidence =1 means
1 crossover event interferes with another crossover event
True genetic distance may be greater than observed frequency. the genes are far apart IS/NOT explanation of phenomenon
In order to localize or map genes on a human chromosome, It is necessary for researchers to collect data from .
genetic analysis/cytological analysis- construct chromosome maps by counting the number of crossovers as well as recombinant chromosomes. Chiasmata is counted through cytological analysis, where as recombinant chromosomes are counted through genetic analysis
which study of genetics shows how different mutations can affect gene function?
Human genome project purpose
To determine sequence of nucleotides in the DNA of the human genome. Sequencing the DNA of a genome provides the data to identify and cataloque all the genes of an organism.
Molecular basis of sickle cell is due to amino acid change in one of the hemoglobic subunits. TRUE/FALSE?
What type of cell division is involved in gamete formation?
The process of cell division in sexually reproducing organisms that reduces the number of chromosomes in reproductive cells from diploid to haploid, leading to the production of gametes in animals and spores in plants.
How many chromatids are present in cell (2n=8) in metaphase
Difference between Eukaryotic chromosome and prokaryotic
Euk- linear
Pro- Circular
Events in prophase 1
During prophase I, DNA is exchanged between homologous chromosomes in a process called homologous recombination. This often results in chromosomal crossover. The new combinations of DNA created during crossover are a significant source of genetic variation, and may result in beneficial new combinations of alleles. The paired and replicated chromosomes are called bivalents or tetrads, which have two chromosomes and four chromatids, with one chromosome coming from each parent. At this stage, non-sister chromatids may cross-over at points called chiasmat
Model system best suited for studying human genetic genes?
Mus .musculus- mouse
Events in Meiosis that are not present in Mitosis
Synapsis and crossing over
Tetrad Formation
Separation of homologues
Model systems
Model systems-
Eschericia coli- bacterium - study major players and events during DNA replication
Saccharomyces cerevisiae, Bakers Yeast- Eukaryotic cell
D.Mmelanogaster- Fruit fly- multicellular
Caenorhabditis elegans- Round Worm- Model for animal developement
Danio rerio, Zebrafish- vertebrate developement
Arabidopsis thaliana- Fast growing plant
If dominant trait , the probability that trait will show if it exhibits complete penetrance is
BbTt * BBtt
Proportion that will have B_tt
(4/4) * (2/4) = 8/16
AABBCC * aabbcc
pheno freq of A_bbc_ where _ is dominant or recessive
(3/4) * (1/4) * (3/4) = (9/64)
degree of freedom=
number of data categories - 1
amorphic means
nonfunctional allele
alleles partially functionally
lethal mutations have ratio of
tests for allelism
cross between two recessive mutations. If hybrid progeny show a mutant phenotype then the new mutation and the tester mutation ARE alleles, if they hybrid is a wild type then they are NOT alleles of the same gene
which mutation limits reproduction
sterile mutation
what is it called when allele has overriding effects
Condition in which a single gene influences more than one trait
cinnabar and scarlet both cause bright red eyes. The crossed offspring will all have wild type eyes because they COMPLEMENT. True/False
nitrogenous bases are held together by
hydrogen bonds
These are giant chromosomes produced by interphase replication without division and consisting of many identical chromatids arranged side by side in a cable like pattern
polytene chromosome
Prokaryotic chromosome structure has 50-100 domains or loops which is independently negatively supercoiled. true/false?
Three levels of condensation in order of complexity, lowest to highest are
supercoiling into nucleosomes, chromatin fiber condensation, scaffold formation
Alternate forms of double helix structure
B-DNA (RIGHT HANDED)- conformation that DNA takes under physiological conditions ( low concentration of salts)
A-DNA- (RIGHT HANDED) high concentrations of salts or partially dehydrated state.
Z- DNA- occurs in double helices that ( LEFT HANDED)
Functions of telomeres
1)prevent DNA from degrading the ends of the linear DNA molecules
2)Prevent fusion of the ends with other DNA molecules
3) Facilitate replication of the ends of the linear DNA molecules without loss of termini.
DNA synthesis always goes in what direction
5' - 3'
Without a free 3' hydroxyl present it results in no DNA. why?
DNA replication requires free 3' oh to initiate polymerase activity, done by synthesizing temp. RNA primer which is removed by polymerase 1
the 3' - 5' exonuclease activity of DNA polymerase 1 is
Central dogma
DNA ~ RNA~ Proteins
how many strands of DNA is used as template during transcription
Transcription takes place in
tRNA functions as
adapters between amino acids and codons
Initiation of transcription is characterized by the binding of
RNA polymerase to promoter region of template DNA
sigma subunit initially recognize and binds to __ sequence
RNA polymerase 1, 2, and 3 are used in _______ for ______
transcription, eukaryotes
The sub discipline of genetics that focuses on the structure and function of entire genomes
Study of epigenetic modification across an individuals entire genome
What is a karyotype? List three types of chromosal abnormalities that can be identified with karyotyping. Give one example of human disorder for each abnormality
Karyotype- mapping of chromosomes according to length and size and where the centromeres are located as well as band pattern.

Duplication- Trisomy 21- down syndrome
deletion- Cri Du Chat
Translocation- the inherited form of down syndrome
Give two examples of human traits that are affected by genes and the environment.
Height- height is affected by both genes as well as by what you eat, if you take vitamins, etc
Alcoholism- By genes depending how fast you break down alcohol and environment such as your surroundings and if you have easy access to it
Explain and differentiate between molecular basis of codominance, incomplete dominance, and complete dominance
incomplete dominance- Allele that is dominant is only partially dominant over recessive allele. Ex. red and white roses produce pink roses. Differences among phenotypes could be due to differences in the amount of the product specified by the dominant allele.
Codominant- neither allele is dominant over the other. The alleles contribute independently to the phenotype of the heterozygotes . (Mosiac)
Complete dominance- The Dominant allele conceals the presence of the recessive allele
independent assortment ratio- 1:1:1:1
linked gene ratio
parents: recombinants
Classical ratio: 9:3:3:1
dominant epistasis- 12:3:1
recessive epistasis- 9:3:4
duplicate dominant- 15:1
duplicate recessive- 9:7
Coefficient of coincidence
observed freq of double crossover- expected freq of double crossover
mendels three laws
The Law of Segregation states that when any individual produces gametes, the copies of a gene separate so that each gamete receives only one copy. A gamete will receive one allele or the other. Mendel’s Law of Dominance states that in a cross of parents that are pure for contrasting traits, only one form of the trait will appear in the next generation. Offspring that are hybrid for a trait will have only the dominant trait in the phenotype. The Law of Independent Assortment, also known as "Inheritance Law", states that alleles of different genes assort independently of one another during gamete formation.
what does a gene encode for and how
encodes for proteins. A gene is expressed depending on particular nucleotide sequence and genetic pathway. 1st step is transcription where DNA is transcribed into RNA and then translation where mRNA is translated into proteins.