Genetics Final Exam

Front 1

what is codominant alleles

Back 1

alleles that lack complete dominant and recessive relationships and are both observed phenotypically

Front 2

incomplete dominance alleles

Back 2

alleles that lack dominance relationships and result in heterozygotes that have intermediate phenotype that is distinct from either homozygous parent. "blend"

Front 3

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

Back 3

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

Front 4

Genetic code is said to be triple, degenerate, non overlapping, and universal. comma free, ordered. EXPLAIN

Back 4

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

Front 5

Who was credited with linking gene for eye color in Drosophila

Back 5

Thomas Hunt Morgan

Front 6

What is the basic chromosome number (N)

Back 6

Haploid

Front 7

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?

Back 7

0%

Front 8

An individual with the genotype as XO is known as being female or male?

Back 8

Female

Front 9

The sex determination system in chickens is

Back 9

Z-W

Front 10

Best explanation for a XX and phenotypically male is

Back 10

a small piece of y chromosome containing sRY region is inserted on X chromosome

Front 11

Individual with two kinds of gametes is

Back 11

heterogametic

Front 12

Dosage compensation for x-linked genes is achieved by

Back 12

inactivation of one of females x-chromosome during early developement

Front 13

Why is y chromosome able to pair with x chromosome during meiosis?

Back 13

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.

Front 14

Which study of genetics deals with the analysis of stained chromosomes

Back 14

Cytogenetics

Front 15

The largest and smallest chromosomes are

Back 15

1 and 21

Front 16

What is the term used for one that carries extra sets of chromosomes

Back 16

Polyploid

Front 17

Which implies genetic imbalance

Back 17

Aneuploid

Front 18

polyploids created by hybridization between different species

Back 18

allopolyplids

Front 19

polyploids created by chromosome duplication within a species are called

Back 19

autopolyploids

Front 20

The under or overrepresentation of a chromosome or chromosome segment (implies genetic imbalance)

Back 20

aneuploidy

Front 21

XXY - male - 2n+1

Back 21

Klinefelter

Front 22

X, 45 - FEMALE

Back 22

Turner

Front 23

Triplication of chromosomes

Back 23

Trisomy

Front 24

Missing portion of chromosome

Back 24

Deletion

Front 25

Segment of chromosome detach and attaches to different chromosome

Back 25

Translocation

Front 26

what does 7p refer to?

Back 26

chromosome 7 short arm

Front 27

Crossing over results in

Back 27

recombination

Front 28

what is used to measure intensity of linkage between genes?

Back 28

recombination frequency

Front 29

True/False
Genes linked tightly recombine less

Back 29

True

Front 30

If two genes are not linked they ...

Back 30

independently assort

Front 31

True/False
Crossing over occurs in the late prophase at the time chiasmata can be viewed

Back 31

FALSE
Begins in early stage of prophase when it can't be viewed

Front 32

Five stages of Prophase of meiosis 1

Back 32

Leptonema,
Zygonema- crossing over initiated
Pachynema- Crossing over proceeds
Diplonema- crossing over completed and becomes visible
Diakinesis- chiasmata disappears

Front 33

What method is used to estimate # of crossovers?

Back 33

count chiasmata and recombination chromosomes

Front 34

18 out of 100 chromosomes recovered from meiosis crossover in vg and B. How far apart are they

Back 34

18 centimorgans

Front 35

Coefficient of coincidence =1 means

Back 35

1 crossover event interferes with another crossover event

Front 36

True genetic distance may be greater than observed frequency. the genes are far apart IS/NOT explanation of phenomenon

Back 36

NOT

Front 37

In order to localize or map genes on a human chromosome, It is necessary for researchers to collect data from .

Back 37

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

Front 38

which study of genetics shows how different mutations can affect gene function?

Back 38

Molecular

Front 39

Human genome project purpose

Back 39

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.

Front 40

Molecular basis of sickle cell is due to amino acid change in one of the hemoglobic subunits. TRUE/FALSE?

Back 40

TRUE

Front 41

What type of cell division is involved in gamete formation?

Back 41

meiosis-
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.

Front 42

How many chromatids are present in cell (2n=8) in metaphase

Back 42

16

Front 43

Difference between Eukaryotic chromosome and prokaryotic

Back 43

Euk- linear
Pro- Circular

Front 44

Events in prophase 1

Back 44

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

Front 45

Model system best suited for studying human genetic genes?

Back 45

Mus .musculus- mouse

Front 46

Events in Meiosis that are not present in Mitosis

Back 46

Synapsis and crossing over
Tetrad Formation
Separation of homologues

Front 47

Model systems

Back 47

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

Front 48

If dominant trait , the probability that trait will show if it exhibits complete penetrance is

Back 48

50%

Front 49

BbTt * BBtt
Proportion that will have B_tt

Back 49

(4/4) * (2/4) = 8/16

Front 50

AABBCC * aabbcc
pheno freq of A_bbc_ where _ is dominant or recessive

Back 50

(3/4) * (1/4) * (3/4) = (9/64)

Front 51

degree of freedom=

Back 51

number of data categories - 1

Front 52

amorphic means

Back 52

nonfunctional allele

Front 53

alleles partially functionally

Back 53

hypomorphic

Front 54

lethal mutations have ratio of

Back 54

2:1

Front 55

tests for allelism

Back 55

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

Front 56

which mutation limits reproduction

Back 56

sterile mutation

Front 57

what is it called when allele has overriding effects

Back 57

epistatic

Front 58

Condition in which a single gene influences more than one trait

Back 58

pleiotropic

Front 59

cinnabar and scarlet both cause bright red eyes. The crossed offspring will all have wild type eyes because they COMPLEMENT. True/False

Back 59

True

Front 60

nitrogenous bases are held together by

Back 60

hydrogen bonds

Front 61

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

Back 61

polytene chromosome

Front 62

Prokaryotic chromosome structure has 50-100 domains or loops which is independently negatively supercoiled. true/false?

Back 62

TRUE

Front 63

Three levels of condensation in order of complexity, lowest to highest are

Back 63

supercoiling into nucleosomes, chromatin fiber condensation, scaffold formation

Front 64

Alternate forms of double helix structure

Back 64

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)

Front 65

Functions of telomeres

Back 65

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.

Front 66

DNA synthesis always goes in what direction

Back 66

5' - 3'

Front 67

Without a free 3' hydroxyl present it results in no DNA. why?

Back 67

DNA replication requires free 3' oh to initiate polymerase activity, done by synthesizing temp. RNA primer which is removed by polymerase 1

Front 68

the 3' - 5' exonuclease activity of DNA polymerase 1 is

Back 68

proofreading

Front 69

Central dogma

Back 69

DNA ~ RNA~ Proteins

Front 70

how many strands of DNA is used as template during transcription

Back 70

1

Front 71

Transcription takes place in

Back 71

cytosol

Front 72

tRNA functions as

Back 72

adapters between amino acids and codons

Front 73

Initiation of transcription is characterized by the binding of

Back 73

RNA polymerase to promoter region of template DNA

Front 74

sigma subunit initially recognize and binds to __ sequence

Back 74

-35

Front 75

RNA polymerase 1, 2, and 3 are used in _______ for ______

Back 75

transcription, eukaryotes

Front 76

The sub discipline of genetics that focuses on the structure and function of entire genomes

Back 76

GENOMICS

Front 77

Study of epigenetic modification across an individuals entire genome

Back 77

Epigenomics

Front 78

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

Back 78

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

Front 79

Give two examples of human traits that are affected by genes and the environment.

Back 79

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

Front 80

Explain and differentiate between molecular basis of codominance, incomplete dominance, and complete dominance

Back 80

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

Front 81

independent assortment ratio- 1:1:1:1
linked gene ratio

Back 81

5:5:1:1
parents: recombinants

Front 82

Classical ratio: 9:3:3:1
dominant epistasis- 12:3:1
recessive epistasis- 9:3:4
duplicate dominant- 15:1
duplicate recessive- 9:7

Back 82

gfff

Front 83

Coefficient of coincidence

Back 83

observed freq of double crossover- expected freq of double crossover

Front 84

mendels three laws

Back 84

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.

Front 85

what does a gene encode for and how

Back 85

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.