Genetics- Cormier

Question 1

What parts make up a nucleotide?

Answer 1

nitrogenous base, 5 carbon sugar, and a phosphate

Question 2

Which NTs are purines?

Answer 2

Pure As Gold (2 rings)

-adenine and guanine

Question 3

Which NTs are pyrimidines?

Answer 3

CUT the Py

-cytosine, thymine (DNA), uracil (RNA)

Question 4

What is the difference between heterochromatin and euchromatin?

Answer 4

heterochromatin is wound tightly and not easily transcribed

euchromatin is easily and actively transcribed

Question 5

How many pairs of chromosomes do humans have?

Answer 5

23 (homologous pair of 22 chromosomes and 1 pair of sex chromosomes)

Question 6

What is ataxia?

Answer 6

disease, progressive deterioration of motor skills (1 normal and 1 aberrant chromosome 12 with extra piece from chromosome 4)

Question 7

Do exons or introns become proteins?

Answer 7

exons, and only code about 1% of DNA

Question 8

How is eukaryotic DNA organized?

Answer 8

histones (with lots of arginine and lysine) wrab DNA to make nucleosome which includes about 200 NT pairs of DNA

Question 9

What are the names of histones involved in DNA organization?

Answer 9

2 H2A, 2 H2B, H3 and H4 are the histone core

-H1 is linker that joins DNA cores

Question 10

What do HAT (histone acetyltransferase) enzymes do?

Answer 10

adds acetyl groups to histone tails, added charge loosens DNA to promote transcription

Question 11

What do HDAC (histone de-acetyltransferase) enzymes do?

Answer 11

take acetyl groups off histone tails, silences DNA transcription and DNA compacts

Question 12

How is eukaryotic DNA processed before leaving the nucleus?

Answer 12

5’ 7 methyl guanosine cap added, 3’ poly A tail, and introns spliced out

Question 13

What subunits make up eukaryotic and prokaryotic ribosomes?

Answer 13

eukaryotic- 60S and 40S

prokaryotic- 50S and 30S

Question 14

What size pieces of rRNA make up prokaryotic and eukaryotic ribosomes?

Answer 14

Prokaryotic (3 types): 5S, 23S, 16S

Eukaryotic (4 types): 5S, 5.8S, 18S, 28S

Question 15

What are the distinguishing features of tRNA?

Answer 15

• attaches AA at 3’ end
• has 3’ to 5’ anti-codon
• cloverleaf structure

Question 16

How does DNA replication work for prokaryotes?

Answer 16

DnaA binds at OriC (single point of origin)
-bidirectional replication (2 replication forks)
DnaB = helicase
DnaG = primase
DNA gyrase = like topoisomerase

Question 17

In what direction is all DNA and RNA made?

Answer 17

always made in 5’ to 3’ direction (so template strand is read 3’ to 5’)

Question 18

What are the main functions of Pol 1, Pol 2, and Pol 3? (prokaryotes)

Answer 18

Pol 1 = fill lagging strand gaps, remove RNA primer
Pol 2 = DNA repair
Pol 3 = DNA replication

Question 19

Which parts of the cell cycle are part of interphase?

Answer 19

G1, S1, and G2 (M phase = mitosis, cell division)

Question 20

What is the difference between topo1 and topo2?

Answer 20

topo1 = single strand breaks
topo2 = double stranded break, target for cancer drugs

Question 21

How does telomerase help the dividing cell?

Answer 21

adds back DNA at end of telomere where it’s lost during replication
-reverse transcriptase, adds 5 nucleotide repeating sequence

Question 22

During transcription, what type of bond is formed between incoming nucleotides and complementary NTs on DNA template strand?

Answer 22

ester bonds

Question 23

How do cis and trans regulatory sequences differ?

Answer 23

cis- same side of DNA strand

trans- act from afar

Question 24

In bacteria, what binds to the promoter (TATA box) to associate the polymerase enzyme?

Answer 24

Sigma factor. It dissociates soon after transcription begins

Question 25

In eukaryotes, what do pol 1, pol 2, and pol 3 usually transcribe?

Answer 25

Pol 1 = rRNA Pol 2 = mRNA, miRNA, lincRNA Pol 3 = small RNAs (tRNAs and 5S RNA)

Question 26

How is transcription initiated in eukaryotes?

Answer 26

Pol 2 is main transcription factor - TF2D binds TATA box and binds TF2A and TF2B - other TFs and RNA pol assemble at promoter - TF2H uses ATP to open double helix

Question 27

What sequence is at each end of the intron for splicing?

Answer 27

5' GU AG 3' of intron gets spliced out

Question 28

What structure forms as an intermediate in splicing?

Answer 28

lariat structure

Question 29

What is the start codon, and what does it code?

Answer 29

methionine, AUG

Question 30

What is "wobble"?

Answer 30

the 3rd BP on mRNA or 5' side on tRNA can vary and still code same amino acid

Question 31

Which end of the protein is made first and which end last?

Answer 31

Translation is from N-terminus to C- terminus (corresponds with 5' to 3')

Question 32

What is the order of ribosome assembly on mRNA for eukaryotes?

Answer 32

initiator tRNA first loads on small ribosomal subunit with euk initiation factors - small subunit scans mRNA for AUG - IFs dissociate and large subunit binds

Question 33

What are the 3 ribosomal sites?

Answer 33

E (exit) P (where growing peptide chain attaches) A (where tRNA binds codon)

Question 34

How does translation initiate in prokaryotes?

Answer 34

at Shine Dalgarno sequence, small ribosomal subunit binds

Question 35

What does the antibiotic tetracycline do?

Answer 35

blocks binding of amino-acyl tRNA to A site of ribosome | targets bacteria

Question 36

What does the antibiotic streptomycin do?

Answer 36

prevents transition from translation initiation to chain elongation targets bacteria

Question 37

What does the antibiotic chloramphenicol do?

Answer 37

blocks peptidyl transferase reaction on ribosome | -targets bacteria

Question 38

What does the antibiotic erythromycin do?

Answer 38

binds in exit channel of ribosome and inhibits elongation of peptide chain -targets bacteria

Question 39

What does the antibiotic rifamycin do?

Answer 39

prevents RNA synthesis by binding RNA polymerase | -targets bacteria

Question 40

What does the release of glucocorticoids signal to the body?

Answer 40

released during starvation | signal liver to produce glucose from AAs

Question 41

How is gene expression regulated?

Answer 41

transcriptional control, RNA processing, RNA transport and localization, translational control, mRNA degradation, protein activity control

Question 42

What are homeodomain proteins?

Answer 42

key regulators of animal development, subclass of helix turn helix motif

Question 43

What are the 2 regulatory parts in the lac operon?

Answer 43

to be on, lactose is broken into allolactose which binds to remove repressor - when no glucose, cAMP binds CAP to remove - lac operon is OFF if glucose is present

Question 44

What is epigenetics?

Answer 44

heritable (meiosis, mitosis), reversible changes in genome that regulate gene expression

Question 45

In mammal females, how is one X chromosome turned "off"?

Answer 45

inactivated by XIC (X inactivation center) and XIST (X inactivation specific transcript) -association of XIST RNA with X chromosome is correlated with condensation

Question 46

What addition signals imprinting? What does it do?

Answer 46

add methyl group to cytosine in CG sequence on 5th carbon which causes chromatin condensation -methylation is inherited in progeny DNA

Question 47

If it is a maternally imprinted gene, will either of the mom's gametes be functional?

Answer 47

No, will imprint both genes so all children will have a maternally imprinted gene. -if son gets maternally imprinted gene, will NOT pass along imprinted gene to children

Question 48

What HIV protein transports unspliced HIV mRNA from nucleus to cytoplasm?

Answer 48

Rev

Question 49

In low iron conditions, how does body respond?

Answer 49

Shut off ferritin product by inhibiting translation from IRE-BP in 5'UTR -express transferrin receptor to uptake iron into cell

Question 50

What is Werner Syndrome?

Answer 50

premature aging, caused by genome instability (affects accessory DNA helicase for replication)

Question 51

Where is benzo[a]prene found?

Answer 51

the carcinogen produced by cigarette smoke | -only becomes carcinogenic when oxidized in cells

Question 52

What does cytosine de-aminate to ?

Answer 52

uracil

Question 53

What does 5-methyl Cytosine deaminate to?

Answer 53

thymine (usually missed by proofreading)

Question 54

How are thymine dimers created?

Answer 54

from UV light, binding of adjacent pyrimidine bases

Question 55

What is the process in strand directed mis-match repair?

Answer 55

in euk and prok: MutS binds to mismatched BP, MutL scans nearby DNA for nick (new strand) then MutL triggers degradation Bacteria: no nicks so MutH nicks unmethylated DNA

Question 56

What is the process in base excision repair (BER)?

Answer 56

endonuclease and phosphodiesterase remove sugar base, DNA pol adds new nucleotides, ligase seals nick

Question 57

What is the process for nucleotide excision repair (NER)?

Answer 57

bigger problem: DNA helicase unwinds DNA, DNA pol adds NTs, DNA ligase seals back up

Question 58

What are the 2 solutions for double stranded breaks?

Answer 58

1) nonhomologous end joining- chop off jagged, ligate ends together, lose NTs, Ku protein 2) homologous end joining- more effective and difficult, use homologous chromosomes and recombination mechanisms

Question 59

What genes are involved in recombination in prok and eukaryotes?

Answer 59

Euk: Rad 51 and proteins ATM, Brca1, Brca2 Prok: RecA

Question 60

Where is p53 protein important?

Answer 60

at G1 checkpoint before cell division