genetics midterm 2

Independent Assortment

genes of different chromosomes separate independently from each other

recombinant

shuffling of alleles from parents leads to the production of ________ gametes

syntenic genes

genes located on the same chromosome. So close that they cannot assort independently and therefore are linked genes

true

T/F: genes linked on the same chromosome do not sort independently

true

T/F: linked genes will not crossover and only make parental gametes

false- less likely

T/F: recombination is more likely to occur between closely linked genes than between those farther apart on a chromosome

prophase 1 of meiosis 1

when does crossing over occur

complete genetic linkage

no crossing over occurs between linked genes- only parental gametes are formed

incomplete linkage

when some crossing over occurs

recombination frequency (r)

(# of recombinant genes/ total # of gametes) *100

independent assortment

r = 50%

complete linkage

r= 0%

double crossover

the least frequent genotype in a trihybrid cross

inference (i)

the differences between the expected and observed number of double crossovers. AKA 1-c

coefficient of coincidence (c)

ratio of observed over expected double crossovers

probability of no recombination

1-r

genome simplicity, uncomplicated genotypes, rapid generation times, large numbers of progeny, ease of propagation, numerous heritable differences

what six factors make bacteria useful to geneticists

conjugation

transfer of replicated DNA from a donor to a recipient

transformation

uptake of DNA from the environment

transduction

transfer of DNA from one bacteria to another by a viral vector

singular, circular, introns rare

describe a chromosome of bacteria

operons

group of genes that are transcribed together because they have interacting functions

plasmids

small double-stranded circular DNA molecules containing non-essential genes

F plasmid

plasmid that contains genes that promote its own transfer from donors to recipients

R plasmid

plasmid that carries antibiotic resistance genes that can be transferred to recipient cells

high copy number plasmids

plasmids that replicate independently of the bacterial chromosome so that the number of plasmids per cell can increase rapidly.

low copy number plasmids

plasmids that are present in one or two copies per bacterial cell and usually cannot replicate independently of the bacterial chromosome

Lederberg and Tatum

which experiment discovered conjugation

Davis

which experiment discovered that conjugation requires physical contact

fertility factor (F)

bacterial conjugation requires a __________

uses DNA replication machinery of the cell, inhibits contact with other F+ cells, promotes growth of the pili

what does the fertility factor do in conjugation (F)

oriT

site where transfer starts in either direction aka origin of replication

episome

plasmid that can integrate into the host genome

crossing over

how does the f plasmid integrate into the bacterial chromosome

merozygote

partial diploid

Hfr cell

A bacterial cell in which the F factor has become integrated into the chromosome

false -switch

T/F: genes closer to the oriT transfer later than genes farther away from the oriT

cells die and release their DNA

how does donor DNA enter the environment for bacteria to take up in transformation

true

T/F: the passage of DNA into a recipient in transformation is accompanied by degradation of one of the strands

cotransformation

the closer two genes are, the more likely they will transform recipient together

far apart

low cotransformation frequency =

replicates faithfully, contains information, changes by mutation and can undergo recombination, evolves and adapts

what are 4 impt properties of DNA

deoxyribonucleic acid

what is the full name of DNA

deoxyribose sugar, nitrogenous base, phosphate group

what is a DNA nucleotide composed of

pyrimidines

thymine and cytosine are _______ meaning they have a single ring

purines

adenine and guanine are _______________ and have a double ring

deoxyribonucleotide monophosphates (dNMPs)

what are the building blocks of DNA called

DNA polymerase

what enzyme assembles individual nucleotides into chains

phosphodiester bond

bond that forms between the 3' hydroxyl group of one nucleotide and the 5' phosphate of an adjacent one

sugar-phosphate

what is the backbone of DNA made of

5' -> 3'

dna polymerase works in what direction

hydrogen bonds

bond that forms between the bases of antiparallel strands

Two

how many bonds between A & T

three

how many bonds form between G &C

semi-conservative

what mode does DNA replicate

one

how many oriT are in bacteria

thousands

how many oriT in eukaryotes

topoisomerase

enzyme that will cleave and rejoin along the DNA molecule to relieve tensions in supercoiled DNA

DNA polymerase III

what enzyme adds nucleotides in the 5' -> 3' direction in order to synthesize DNA

primase

what does DNA polymerase bind to in order to function. Synthesizes RNA primers.

leading strand

strand with continuous replication

lagging strand

strand with discontinuous replication and Okasaki fragments

helicase

enzyme that unwinds the double helix

Single stranded binding proteins

proteins that prevent reannealing of separated strands

DNA polymerase I

enzyme that removes and replaces RNA primer with DNA

DNA ligase

enzyme that joins DNA segments

Holoenzyme

a core enzyme plus additional proteins required for proper function

telomerase

enzyme that adds noncoding DNA that can be sacrificed to protect the ends of chromosomes

telomeres

Repeated DNA sequences at the ends of eukaryotic chromosomes.

true

T/F: the efficiency of telomerase declines with age

PCR

method to exponentially increase the amount of DNA in a sample. Needs MgCl and dNTP

negative

what is the charge of DNA

negative to positive

movement of DNA in agarose gel electrophoresis

denaturation 95C, annealing 60C, extension 72C

temperature and sequence for PCR

Taq DNA polymerase

what enzyme extends primers in PCR at 72C

Sanger sequencing

A procedure that uses ddNTPs in order to terminate the chain and stop replication at each appearance of a certain nucleotide

one

how many primers in sanger sequencing

two

how many primers in PCR

DNA -> RNA -> protein

what is the central dogma

uracil and ribose sugar

what are the two main differences in structure of DNA and RNA

deoxyribose has H while ribose has OH

what is the difference between deoxyribose sugar and ribose sugar

two

uracil forms _______ H bonds with adenine

methyl group

difference between thymine and uracil is

RNA polymerase

enzyme that catalyzes the addition of ribonucleotide to the 3' end of the nascent strand, and forms the phosphodiester bonds between nucleotides in transcription

carry info

main function of DNA

mRNA

type of RNA used for transfer of info from DNA to protein

rRNA

type of RNA that are components of the ribosome

tRNA

type of RNA that serves as adapters in translation

false- not for this course

T/F: the promoter is part of the gene

gene

the physical unit of heredity, composed of DNA sequence that is transcribed and encodes for a protein or another functional transcript

sigma subunit

core enzyme must have

promoter

double stranded DNA sequence that is the RNA polymerase binding site and is required for the initiation of transcription

consensus sequences

-10 and -35 are ___________ and makes the strand recognizable by RNA polymerase

intrinsic termination

a mechanism dependent only on the presence of the repeat. induces secondary structure needed for termination

RNA polymerase I

transcribes three ribosomal RNA genes

RNA polymerase II

transcribes protein coding genes and most small nuclear RNA genes

RNA polymerase III

transcribes tRNA, one small nuclear RNA, and one ribosomal RNA

three

how many promoters in eukaryotic cells. Ex: TATA box

transcription factors

RNA pol II needs what to bind

enhancers

interact with transcription factors via a protein bridge. Can be tens of thousands of bp away