Ch 10: Nature of Gene and Genome

Question 1

Law of Segregation

Answer 1

only one of two copies of heritable factor (gene) contricuted ot offspring

Question 2

Low of Independent Assortment

Answer 2

Segregation of one gene pair has no influence on segregation of other gene pair

(Revealed by dihybrid crosses)

Question 3

Two types of cell division

Answer 3

mitotic (produces more cells)

meiotic (prodeces cell siwht half of chromosomes)

Question 4

non-linked traits

Answer 4

the traits studied by Menel

Obey the law of independent assortment

Question 5

Genetic Recombination

Answer 5

Genes onthe same chromosome do not alway segregate together (incomplete linkage)

Question 6

What does frequency of genetic recombination depend on

Answer 6

the distance apart on the chromosome

further apart, the more likely recombinaiton events occur

Question 7

Chromosome puff

Answer 7

Polytene chromosomes

??? know more ???

Question 8

Griffith experiment

Answer 8

demonstrates the transformation principle

-> Bacteria uptake plasmids from their environment

Question 9

Hershey-Chase experiment

Answer 9

used T4 bacteriophage to infect bacteria

demonstrated that DNA was the genetic material

nucleotide triphosphates labeled with p32, which is incorperratecd into DNA

Question 10

Requirements for Genetic Material

Answer 10

storage of information: heritable instructions

self-suplicaiton and ingeritance: transmission from cell to daughter cells

Expression of genetic mateiral

Question 11

Implications of the watson-crick model.

How do they demonstrate the 3 requirements genetic mateirla must have?

Answer 11

Storage
= proposed that base sequence endoded genes

Replicaiton
= proposed that strands could seperate and serve as templates for new synthesis

Expression
=???

Question 12

Relaxed vs supercoiled DNA

Answer 12

Supercoiled DNA is more tightly compacted

travels faster in gel

supercoiling plays a roe in DNA replication and transcription

Question 13

DNA supercoiling and DNA Topoisomerases

Answer 13

DNA topoisomerases can alter DNA supercoiling

DNA Topo-I cuts one strant adn permits relaxation

DNA Topo-II cuts both strands adn passes other region of DNA through break

Question 14

Reactions catalyzed by topoisomerases

Answer 14

1) supercoiling relaxation
2) Knotting/ unknotting
3) Catenation of DNA molecules (and decatenation)

Question 15

GC contents and genome complexity

Answer 15

Genome complecity can be partially determined by DNA denaturation

GC content determines melting temperature (3x h-bonds), and the higher the GC content, the higher the melting temperature

Question 16

Does single stranded or double stranded DNA absorb stronger at 260nm UV

Answer 16

ssDNA

Question 17

AT rich DNA regions

Answer 17

intergenic// non-coding DNA ???

Question 18

Three classes of DNA in the eukaryotic genome

Answer 18

Highly repeated

moderately repeated

nonrepeated (unique)

Question 19

Highly repetitive DNA

Answer 19

satellite, minisatellite, microsatellite DNAs

Question 20

Moderately repeated DNA

Answer 20

tRNA and rRNA genes

Question 21

nonrepeated (unique) DNA

Answer 21

DNA coding for single genes

Question 22

Satellite DNA

Answer 22

monomer length from several to several hundred bp

large clusters of up to millions of base pairs

normally localized o centromeric and telomeric regions of the chromosoems

Question 23

Minisatellite DNA

Answer 23

monomer repeates from 12 to 100 bp

clustered repeats up to 3000 monomers per cluster

repeat length varies between individuals

Question 24

Microsatellite DNA

Answer 24

simple sequence repeats (1-5 bp)

small slusters of 50-100 bp

scattered through genome

highly variable between individuals

• > monomer repeat number varies
• > used for population of forensic studies

Question 25

Satallite DNA function

Answer 25

CenP-B sequence in human satellite DNA binds CEN-B protiens to help for the kinetochore Uniformity of satellite DNA length =may be related to nucleosome phasing (every 200 bp you have a nucleosome) = helps with DNA organization Satellite DNA transcription =may form ribozymes -initiate histone H3 methylation =heterochromatization

Question 26

Evolution of Satelite DNAs

Answer 26

see slides Mutations in satellite monomer can bind mutated centromeric protien. homogenization over time could lead to change in chromosome structure

Question 27

See slides for in situ hybridization and satellite DNA

Answer 27

found that satellite DNA is at the centromere?/

Question 28

Two categories of Triplet expansion diseases

Answer 28

Type I = CAG repeat (neurodegenerative) =coding regions of genes Type II = variety of repeats =non-coding regions of genes

Question 29

Huntington's Disease

Answer 29

neurodegenerative (type i Triplet expansion) Huntington gene normally has 6-35 copies of CAG repeat (polyglutamine) Affected individuals have more than 35 copies huntington protein forms aggregates dominant genetic disorder exhibits genetic anticipation =severity increases from genertion to generation

Question 30

Fragile X syndrome

Answer 30

Type two triplet expansion disease Normal gene has 5-55 copies of CGG FMR1 gene (function unknown) carriers have 60-200 repeats affected individuals have more than 200 repeats X-chromosome highly unstable (fragile) loss of function mutation

Question 31

Genome stability

Answer 31

gene duplicaiton has three fates diverge and acquire new function diverge and one loses function (pseudogene) both copies retain same function genes can duplicate by unequal crossing over, a mitotic event where there is a slight missalignment of chromosomes

Question 32

How can a whole genome duplicate? i.e. diploid to polyploid

Answer 32

2n to 4n conversion of haploid gamates to diploid gamated this can occur during a non-dysjunction even from mitosis (chromosome homologs do not separate and both copies go to the same cell)

Question 33

What are the three fates of gene duplication

Answer 33

nonfuctionialization (psuedogene) neofunctionialization (new gene) subfunctionialization (wonky gene, change of spatial or temporal expression)

Question 34

Gene orthologues

Answer 34

same gen in two different species gene is seperated by speciation

Question 35

Gene paralogues

Answer 35

two genes (duplicted) in the same organism may be in a differnt location 2nd copy can eventually take up a new function

Question 36

Transposable elements

Answer 36

inverted repeats at either end of the transposon = recognized by transposase enz Direct repeats generated in target DNA ``` Usually integrate (jump) randomly into new part of genome = can disrupt genes (cause mutations) ```

Question 37

nonreplicative transposition

Answer 37

cut and paste pathway

Question 38

Replicative transposition

Answer 38

Have their own origin of replication [regular DNA pol] ???

Question 39

Retrotransposon

Answer 39

capy and paste pathway that goes through an RNA intermediate

Question 40

P-elements

Answer 40

eild-encoded viral transposons that were transfered to wild type Drosofilla Morgans original stocks did not have P-elements Flies descended from wild caught strains have P-elements

Question 41

Funciton of transposable elements

Answer 41

form part of some gene regulatory regions can combine genes to form novel genes or novel functions sometime evolve into function genes like the telomerase gene, an enzyme in germline cells that is used to extend telomeres

Question 42

Look up lcture video on sequencing and mapping genomes???

Answer 42

CH 10 jan 15

Question 43

SNPs and gene mapping

Answer 43

may be useful as makers approx 3 million SNPs in the human genome if found in coding regions they may affect the funciton of the gene (may be assiciated or linked with disease) used in haplotype maps

Question 44

SNPs and alzheimers

Answer 44

Apolipprotien (ApoE) gene has two SNPS thre total alleles each differ by one nucleotide E2 (cys112 and cys158) E3 (cys112 and arg158) E4 (arg112 and arg158) individuals wiht at least one E4 allele are prone to alzheimers individuals with E2 allele are less prone to aquiring alzheimers