year one revision

Question 1

what is a nucleoside?

Answer 1

base and sugar

Question 2

what is a nucleotide?

Answer 2

nucleoside and phosphate group

Question 3

DNA pentose sugar

Answer 3

deoxyribose

Question 4

RNA pentose sugar

Answer 4

ribose

Question 5

bases structure

Answer 5

consists of heterocyclic rings of carbon and nitrogen atoms.

Question 6

DNA and RNA basic structure

Answer 6

phosphate - pentose sugar - nitrogenous base

Question 7

how many rings do purines have?

Answer 7

two interlocked rings

Question 8

how many rings do pyrimidines have?

Answer 8

single ring

Question 9

which bases are purines?

Answer 9

adenine and guanine

Question 10

which bases are pyrimidines?

Answer 10

cytosine, thymine and uracil

Question 11

what are the common bases in DNA and RNA?

Answer 11

adenine, cytosine and guanine

Question 12

what base is present in DNA but not RNA?

Answer 12

thymine

Question 13

what base is present in RNA but not DNA?

Answer 13

uracil

Question 14

what does uracil lack that is found in thymine?

Answer 14

5-methyl group

Question 15

how is a base attached to a sugar?

Answer 15

covalently bonded by N-glycosidic bond

Question 16

which form of DNA is most common?

Answer 16

B-DNA

Question 17

A-DNA structure

Answer 17

right handed
pitch of 3.2nm
11 bases per turn

Question 18

B-DNA structure

Answer 18

right handed
pitch of 3.4nm
10 bases per turn

Question 19

Z-DNA structure

Answer 19

left handed
pitch of 4.5nm
12 bases per turn

Question 20

codon definition

Answer 20

sequence of three nucleotides that correspond with a specific amino acid or stop signal

Question 21

composition of bacterial genomes

Answer 21

single circular chromosome

considered haploid

Question 22

plasmid definition

Answer 22

extra-chromosomal DNA, often found in the cytoplasm of a bacterial cell,which replicates independently

Question 23

histone definition

Answer 23

small, basic proteins bound tightly to DNA

Question 24

function of histones

Answer 24

structural support

involved in packaging

Question 25

histone charge

Answer 25

positive

Question 26

chromatin definition

Answer 26

DNA- protein complex

Question 27

chromosome packaging at interphase

Answer 27

low packaging

Question 28

what does first level of DNA packaging involve?

Answer 28

periodic coiling of the double helix around histone proteins

Question 29

nucleosome definition

Answer 29

a length of DNA coiled around a core of histones | 146 base pairs coiled arounf 8 histones

Question 30

how are adjacent nucleosomes connected?

Answer 30

by linker DNA ( can be as long as 114bp) | histone H1 binds to linker DNA close to the nucleosome

Question 31

euchromatin definition

Answer 31

loosely packaged DNA can be transcribed weak binding of histone H1

Question 32

heterochromatin

Answer 32

tightly packaged DNA cannot be transcribed strong binding of histone H1

Question 33

what must chromosomes conain in order to be copied and transmitted accurately?

Answer 33

a centromere replication origins telomeres

Question 34

chromosome packaging during metaphase

Answer 34

highly packaged so they do not get tangled during cell division

Question 35

linear size of chromosomes during metaphase

Answer 35

0.01% of the fully extended chromosomal DNA

Question 36

what enzyme causes DNA strands to unwind?

Answer 36

DNA helicase

Question 37

At what end are the nucleotides added the the DNA strand?

Answer 37

3' end

Question 38

what happens to deoxynucleoside triphosphates before they are added to the DNA strand?

Answer 38

DNA polymerase cleaves the precursors between the alpha and beta phosphate groups creating deoxynucleoside monophosphate that can be added

Question 39

what does semi-conservative DNA replication mean?

Answer 39

each daughter duplex contains one strand from the original DNA duplex and one newly synthesised DNA strand

Question 40

what is the direction of growth on the leading strand?

Answer 40

5' to 3'

Question 41

what is the direction of growth on the lagging strand?

Answer 41

3' to 5'

Question 42

what is the most common secondary structure of RNA in a cell?

Answer 42

hairpin

Question 43

what does the hairpin RNA structure consist of?

Answer 43

stem and loop arrangement | RNA strand loops back and complementary bases pair forming the stem and leaves a small loop of unpaired bases

Question 44

how much of the total cellular RNA does rRNA make up?

Answer 44

80%

Question 45

what is rRNA

Answer 45

ribosomal RNA

Question 46

what is tRNA

Answer 46

transfer RNA | acts as an adapter molecule between the nucleotide sequence of the mRNA molecule and amino acid

Question 47

how much of the total cellular RNA does tRNA make up?`

Answer 47

15%

Question 48

how is mRNA modified in eukaryotes?

Answer 48

addition of 5' cap addition of 3' polyadenyl tail introns spliced by spliceosomes. only after this happens can the mature mRNA leave the nucleus

Question 49

why is a 5' cap added to mRNA?

Answer 49

allows recognition by the ribosome

Question 50

how is a 5' cap added to mRNA?

Answer 50

add a G to 5' end which is then methylated

Question 51

why is a 3' polyadenyl tail added to mRNA?

Answer 51

increases the half life and increases the efficiency of translation

Question 52

what enzyme adds the 3' polyadenyl to mRNA?

Answer 52

poly (A) polymerase

Question 53

which RNA polymerase is responsible for transcribing all protein-coding genes in the nucleus?

Answer 53

RNA polymerase II

Question 54

which DNA strand is used as a template during transcription?

Answer 54

antisense strand

Question 55

what is the process of transcription?

Answer 55

DNA helicase unwinds the DNA locally as RNA polymerase advances ribonucleoside triphosphate precursors are cleaved by the polymerase to form ribonucleoside monophosphates which are added on nucleotide as a time to the 3' hydroxyl group of the previous nucleotide

Question 56

what are transcription factors and what do they do?

Answer 56

proteins which bind to the promoter and position and guide the RNA polymerase to help transcription proceed effectively

Question 57

what is the start codon?

Answer 57

AUG

Question 58

what are the stop codons?

Answer 58

UAG UAA UGA

Question 59

what is a point mutation

Answer 59

when a single base pair is altered

Question 60

what are the types of point mutation

Answer 60

substitution deletion addition

Question 61

what are the possible effects of point mutations

Answer 61

silent- no effect, the base change still encodes for the same amino acid missense- the base change now encodes for a different amino acid nonsense- the base change encodes for a stop codon

Question 62

what is an open reading frame?

Answer 62

section of DNA between a start and stop codon that is able to be translated no overlaps and no gaps

Question 63

how many reading frames does double stranded DNA have?

Answer 63

6

Question 64

what does cDNA stand for?

Answer 64

complementary DNA

Question 65

what are exons?

Answer 65

protein coding regions

Question 66

what are introns?

Answer 66

non protein coding regions