U2 - Genetics

Question 1

what is a nucleic acid

Answer 1

large biomolecules essential in all cells and viruses

Question 2

purine

Answer 2

double carbon ring structure with adenine and guanine

Question 3

pyrimidine

Answer 3

single carbon ring structure with thymine and cytosine and uracil (RNA)

Question 4

DNA vs RNA

Answer 4

DNA
→ double stranded
→ deoxyribose as sugar base
→ stays in nucleus
→ inheritance of genetic material
→ thymine

RNA
→ single stranded
→ ribose as sugar base
→ can leave nucleus
→ protein synethsis
→ uracil

Question 5

difference in hydrogen bonds holding the nucleic acids tgt

Answer 5

A has double hydrogen bonds to T
G has triple hydrogen bonds to C

Question 6

what is nucleotide (monomer)

Answer 6

A molecule that is the basic building block of the nucleic acids DNA and RNA

Question 7

what is phosphodiester bond

Answer 7

this bond links 5’ phosphate group of one nucleotide with the 3’ hydroxyl group of another nucleotide

Question 8

what is glycosyl bond

Answer 8

bond between sugar and nitrogenous base in nucleic acid (DNA and RNA)

Question 9

ATP process
ADP process

Answer 9

a-p-p-p (ATP) releases energy meaning it is CATABOLIC

app (ADP) puts in energy meaning it is ANABOLIC

Question 10

distance between each nucleotide in DNA and distance between each full turn

Answer 10

between nucleotide: 0.34nm
1 complete turn: 3.4nm

Question 11

erwin chargaff

Answer 11

→ 1950
→ Chargaff’s rule; discovered A pairs with T and G pairs with C

Question 12

rosalind franklin

Answer 12

→ 1953
→ used x-ray difffraction to discover helical nature of DNA

Question 13

watson and crick

Answer 13

→ 1953
→ made the model of DNA

Question 14

histone

Answer 14

a pos. charged protein that DNA is bound to in a chromosome

Question 15

nucleosome

Answer 15

a complex of 8 histones enveloped by DNA

Question 16

telomere

Answer 16

a long sequence of repetitive, non-coding DNA found at end of chromosomes

Question 17

centromere

Answer 17

constricted region of chromosome that holds two replicated chromosome strands together

Question 18

AT and CG diference

Answer 18

AT is held by double bonds
CG is held by triple bonds

Question 19

components of DNA (draw)

Answer 19

chromosome, centromere, chromatid, supercoiled 30nm fibre, chromatin fibre, nucleosome, nucleosomes, histones, DNA double helix (20nm)

Question 20

what did fred griffith discover and when

Answer 20

1928 - transformation, R-forms look rough (no capsule) and S-form looks smooth (Has capsule), heat killed cells and he studied bacteria causing pneumonia

Question 21

what did beadle and tatum discover and when
draw out diagram to undertand

Answer 21

1941- investigated the ‘one-gene-one-enzyme’ hypothesis using bread mould.

A———->B———->C———>D——–>E
E1. - E2. - E3.
gene 1 - gene 2 - gene 3

his theory found that x-rays destroy gene 2 therefore no enzymes and mould dies unless supplmented with C,D, or E

Question 22

lac vs trp operon?

Answer 22

lac operon is inducible and encodes enzymes that break down lactose for food

trp operon is repressible that encodes enzymes that make tryptophan (AA)

Question 23

promoter region vs operator region

Answer 23

promoter region is DNA sequence where RNA polymerase binds to initiate transcription

Operator is the DNA segment where the repressor molecule binds to operon

Question 24

Explain how gene regulation is different in eukaryotic cells and prokaryotic cells.

Answer 24

prokaryotes don’t have nucleuses so the process is much simpler, transcription and translation can occur at the same time at opposite ends of mRNA.

in eukaryotic cells, its regulated by repressors as well as by transcriptional activators. eukaryotes have to transcribe and then have a process for mRNA processing

Question 25

define operon, operator, repressor

Answer 25

operon - link of genes that regulates other genes that are responsible for protein synthesis operator - segment of DNA where repressor binds to, preventing transcription of certain genes repressor - protein that binds to the operator sequence to inhibit gene transcription

Question 26

why is it advantageous to the cell to have some of its genes under regulation

Answer 26

To control when proteins are synthesized and when they are broken down. - Allows cells to conserve energy and space. - Convenient and more efficient to synthesize proteins only when needed..

Question 27

how to determine between inducers or corepressors

Answer 27

inducers - increase transcription corepressors - decrease transcription

Question 28

p-site vs a-site

Answer 28

p site - (peptidyl) the second binding site for tRNA in the ribosome. a site - (aminoacyl) the first binding site in the ribosome

Question 29

codon vs anti codon

Answer 29

codon - three-nucleotide sequence found on mRNA that codes for a certain amino acid during translation anticodon - three-nucleotide sequence found on tRNA that binds to the corresponding mRNA sequence.

Question 30

start codon vs stop codon

Answer 30

start codon initiates the translation stop codon ends the translation

Question 31

Three types of RNA must be functioning properly to ensure normal protein synthesis. Identify the three types of RNA that are needed and explain the critical role that each one plays during translation.

Answer 31

mRNA - carries information from DNA in nucleus to ribosomes tRNA - carries AA to ribosomes during translation (builds AA chain) rRNA - forms ribosomes (essential in protein synthesis)

Question 32

The following sequence was isolated from a fragment of mRNA: 5’ – GGC CCA UAG AUG CCA CCG GGA AAA GAC UGA GCC CCG – 3’ Translate the sequence into protein starting with the start codon.

Answer 32

5’ – GGC CCA UAG AUG CCA CCG GGA AAA GAC UGA GCC CCG – 3’ AUG is the start codon (met) translated AUG (start) CCA CCG GGA AAA GAC UGA (stop) : Met-Pro-Pro-Gly-Lys-Asp

Question 33

Differentiate between introns and exons

Answer 33

introns - non coding sections of RNA transcript exons - sections of DNA that code for proteins

Question 34

differences in prokaryote and eukaroyote transcription

Answer 34

prokaryotes - coupled with translation - lacks introns meaning no excision (removing/cutting out) eukaryotes - occurs in nucleus - spliceosomes (large RNA protein) cut introns out and exons join together