module 3

Question 1

genome

Answer 1

• entire complete set of genetic material in a cell

Question 2

Ploidy

Answer 2

• number of copies of the genome (n)
• can be haploid, diploid, triploid
• not static: vary throughout ones lifetime

Question 3

Chromsomes

Answer 3

• composed to genetic material (DNA/RNA coiled around histones)
• can be circular or linear

Question 4

Outline the 2 types of mutaions

Answer 4

1. spontaneous: occurs without external cause - replication errors
2. induced: by mutagens (radiation and chemical)

Question 5

alleles

Answer 5

variant of genes caused by mutations and can be different lengths

Question 6

Point mutations

Answer 6

change in a single nucleotide
Base substitution
1. silent: no effect
2. missense: changes the amino acid
3. nonsense: results in a stop codon
Base deletion or addition
1. frameshift: causes the reading frame to shift

Question 7

Can mutations occur in non-coding reigons

Answer 7

Yes, even though they are not translated
- changes can affect timing, location or level or gene expression

Question 8

difference between horizontal transmission and vertical transmission

Answer 8

horizontal occurs when genetic info is passed to a member of the same generation whereas vertical refers to the passing of info to the next generation

Question 9

recombination

Answer 9

crossing over between chromosomes
can occur between sister chromatids in a chromosomes but doesnt result in genetic difference

Question 10

What is aneuploidy and list 2 types

Answer 10

caused by non-disjunction
trisomy: 3 chromosomes (down syndrome)
monosomy: one chromosome

Question 11

List the different mechanism of sex determination found in nature

Answer 11

• Environmental: incubation temp of reptilian eggs
• genetic: ploidy, ratio of autosomes to sex chromosomes
• sex determining gene

Question 12

Heterogametic and homogametic

Answer 12

hetero = XY and homo = XX

Question 13

Difference between non-disjunction at meiosis 1 and meiosis 2

Answer 13

at meiosis 1: homologous chromosomes fail to seperate
at meiosis 2: sister chromatids fail to seperate

Question 14

Mendel’s first law

Answer 14

alleles always segreagate away from each other gametes

Question 15

purpose of reciprocal cross

Answer 15

determine whether trait is sex-linked
is sex-linked when phenotypes of offspring are different when genotypes are swapped

Question 16

mendel’s second law

Answer 16

independen assortment: alleles of seperate genes will always segregate independently into gametes

Question 17

Why is recombination in linked gene less likely to occur

Answer 17

the closer loci are the lower the frequency of a recombination event

Question 18

Test cross

Answer 18

cross to homozygous recessive individual test for linkage

Question 19

back cross

Answer 19

cross between offspring and parent

Question 20

incomplete dominance

Answer 20

one functional allele is not sufficient to generate wild-type phenotype

Question 21

co-dominance

Answer 21

each allele is sufficient to generate a phenotype

Question 22

monogenetic trait

Answer 22

trait controlled by one gene

Question 23

polygenetic trait

Answer 23

trait controlled by more than one gene
genes can interact to build traits

Question 24

Different transcription of genes

Answer 24

1. constitutive: expressed under all conditions
2. regulated: expressed under certain conditions
   - positive control: increase/turning on transcription
   - negative control:decrease/turning off transcription

Question 25

Regulation of lac operon: lactose absent

Answer 25

LacI binds to LacO, blocking RNA polymerase from binding and transcribing

Question 26

Regulation of lac operon: lactose is present

Answer 26

lactose binds to LacI preventing it from binding to LacO
RNA polymerase is able to bind ad transcribe it to create enzymes for lactose breakdown

Question 27

Difference between temperol and spacial expression

Answer 27

temeperol expression refers to when it is expressed chagnes overtime and spacial refers to where it is expressed changes overtime