genetics exam 2

Question 1

Genes exhibit linkage while on the same chromosome or on different chromosomes?

Answer 1

same chromosomes

Question 2

what type of gametes result from complete linkage?

Answer 2

parental or non-crossover gametes

Question 3

The percentage of offspring resulting from recombinant gametes will vary depending on what?

Answer 3

the distance between the two genes along the chromosome

Question 4

The distance between two loci on a single chromosome`

Answer 4

interlocus distance

Question 5

what is chiasmata?

Answer 5

synapsed chromosomes that wrap around each other

Question 6

Two genes located close to each other along the chromosome are less likely or more likely to have a chiasma form between them?

Answer 6

less likely

Question 7

The frequency of exchange is an estimate of what?

Answer 7

the relative distance between two genes along the chromosome

Question 8

What are map units and what is another name for them?

Answer 8

stands for 1 percent recombination between two genes on a chromosome. / centimorgans

Question 9

A single crossover alters the linkage between two genes only if what?

Answer 9

if the crossover occurs between those genes

Question 10

What could be expected when two linked genes are 50 map units apart?

Answer 10

crossovers in 100% of tetrads

Question 11

What can double crossovers determine?

Answer 11

the order of three genes on the chromosome

Question 12

What must the genotype of the parent be for three point mapping to be conducted?

Answer 12

heterozygous for all three genes under consideration

Question 13

In DCO’s, non-crossover F2 phenotypes occur how much?

Answer 13

in the greatest proportion of offspring

Question 14

In DCO’s, double crossover phenotypes occur in what proportion?

Answer 14

in the smallest proportion

Question 15

What did the Luria-Delbruck experiment of fluctuating numbers of colonies with mutations prove?

Answer 15

that mutations are spontaneous not produced

Question 16

Bacterial resistance arise from mutations that exist before or after exposure to bacteriocide?

Answer 16

Before

Question 17

When do mutations generally occur?

Answer 17

randomly

Question 18

What is bacterial genetic recombination?

Answer 18

a non-reciprocal transfer of genetic material from one bacterium to another

Question 19

What are the three types of genetic recombination in bacteria?

Answer 19

Conjugation
Transformation
Transduction

Question 20

What is an auxotroph?

Answer 20

a mutant organism that requires an additional nutrient that the normal strain does not

Question 21

What is a prototroph?

Answer 21

a microorganism that has the ability to synthesize its own cell constituents

Question 22

What is the F factor in F+ bacteria?

Answer 22

a small circular, double standed DNA molecule

Question 23

How many genes are on the F factor?

Answer 23

40

Question 24

What is a cell called when the plasmid integrates into the chromosome?

Answer 24

Hfr cell

Question 25

What is a merozygote?

Answer 25

partially diploid cell

Question 26

What is a heteroduplex?

Answer 26

when a piece of DNA from outside the cell comes in and becomes part of the chromosome

Question 27

What are the two types of transduction?

Answer 27

generalized and specialized

Question 28

what does a bacterial chromosome fold into?

Answer 28

nucleoid body

Question 29

Mutations that create auxotrophs have lost what?

Answer 29

the ability to synthesize a substance required for growth

Question 30

What is the nomenclature for a gene?

Answer 30

leu2+ ---> wild type gene required for leucine synthesis

Question 31

What is the nomenclature of a phenotype?

Answer 31

Leu+ ---> a bacterium that does not need leucine to grow | Leu ---> a bacterium that needs leucine to grow

Question 32

What does 90% of E. Coli genome encode?

Answer 32

proteins

Question 33

How many base pairs does E. Coli have?

Answer 33

4.6 million

Question 34

What do plasmids do for E. coli?

Answer 34

can carry resistance to antibiotics and toxic substances.

Question 35

What is the size range of plasmids?

Answer 35

1kb-3Mb

Question 36

What does virulence mean?

Answer 36

relative ability to initiate illness

Question 37

what are the symptoms of tuberculosis?

Answer 37

persistent cough, shortness of breath, weakness

Question 38

How long are the antibiotics prescribed for TB?

Answer 38

6 months

Question 39

What is LHON?

Answer 39

Leber's hereditary optic neuropathy -maternally inherited disease resulting from a mutation in the mitochondrial gene that causes reduced oxidative phosphorylation

Question 40

what is infectious heredity?

Answer 40

cytoplasmic microorganism that affects phenotype

Question 41

what is organelle heredity?

Answer 41

inheritance from only one parent (usually maternal) - mitochondria - chloroplast

Question 42

what is a nucleoid?

Answer 42

the DNA-containing region within the cytoplasm in prokaryotic cells

Question 43

how many tRNA genes does the human mtDNA have?

Answer 43

22

Question 44

Mitochondrial and chloroplast genomes are semiautonomous because why?

Answer 44

they require cooperation between organelle and nuclear genomes

Question 45

why do mtDNA and cpDNA have higher mutation rates than nuclear DNA?

Answer 45

- more exposure to oxidative damage | - lack of protection from histone proteins that bind eukaryotic DNA

Question 46

What is the difference between homo and heteroplasmic cells?

Answer 46

homo contain only one type of organelle genome and hetero contain a mixture of genomes

Question 47

What are the three petite mutants of saccharomyces?

Answer 47

- segregational - neutral - suppressive

Question 48

What did Griffith find out in his experiments?

Answer 48

that something from the heat-killed S bacteria transformed the living R bacteria into S

Question 49

How many sub-units make up DNA and how many make up Protein?

Answer 49

4 / 20

Question 50

Who provided convincing evidence that DNA is genetic material?

Answer 50

Alfred Hershey and Martha Chase in 1952

Question 51

What was found when bacteriophage infected e. coli are grown in 32P medium?

Answer 51

that the progeny are radioactive unlike that of 35S medium grown progeny.

Question 52

When did Watson and Crick propose their double helix model of DNA structure?

Answer 52

1953

Question 53

What were the three major findings of chargaff's base-composition studies?

Answer 53

- A is proportional to T; C is proportional to G - The sum of purines = sum of pyrimidines - Percentage of C+G is not necessarily equal to percentage of A+T (refutes the ____tetranucleotide hypothesis____, which stated that A,C,G,&T are in equal amounts)

Question 54

how wide is a DNA strand?

Answer 54

20A

Question 55

How does RNA differ from DNA?

Answer 55

- Ribose replaces deoxyribose | - Uracil replaces Thymine

Question 56

What are the three major types of RNA?

Answer 56

- mRNA - rRNA - tRNA

Question 57

What are the techniques for characterizing DNA and RNA?

Answer 57

- Absorption - Sedimentation behavior - Denaturation/renaturation - electrophorisis