GENO- Transmission of genetic information

Question 1

what is the central dogma

Answer 1

the central dogma is the process by which the instructions in DNA are converted into a functional product

DNA - RNA- protein - phenotype

Question 2

what is the role of RNA polymerase

Answer 2

unwind the DNA and recruit nucleotides to generate a new mRNA molecule

Question 3

how is RNA polymerase able to bind to a DNA strand

Answer 3

DNA has different regions:

transcription unit = used to produce the RNA

TATA box- upstream from the transcription unit - transcription factors bind here to allow the binding of RNA polymerase

Question 4

outline mRNA processing

Answer 4

begins at transcription
a methylate cap is added to 5’ end
transcription happens and pre mRNA is released
cleavage factors bind to specific regions on the mRNA
polyA polymerase cleaves the 3’ end
once cleaved a poly A tail is added

Question 5

outline the process of mRNA splicing

Answer 5

introns have signal’s that are used in the splicing process

from the 5’ end - GU, A branch site, pyr-rich region, 3’ AG

proteins form a complex near the GU region

the RNA forms a spliceosome

intron is cleaved at the 5’ GU sequence which forms a lariat at the A branch site
intron is cleaved at the 3’ AG region and the two exons are ligated together

the introns are released from the spliceosome and degraded

Question 6

outline the process of protein formation from mRNA

Answer 6

elongation
mRNA has a poly A tail at 3’ end and a methylated cap at 5@ end

translation begins at the methylated cap at the 5’ end where a ribosome attaches

tRNA contains an anticodon which is complementary to the mRNA codon - attached to tRNA = AA

tRNA molecules bring complementary AA to the chain which are formed into a polypeptide chain (via peptide bonding)

this happens until the ribosome encounters a stop codon

this is then a protein - primary structure = sequence of AA

Question 7

define sense DNA strand

Answer 7

the same sequence as the mRNA molecule

Question 8

define antisense DNA strand

Answer 8

used as a template for the mRNA molecule so it has the same sequence as the sense strand

Question 9

compare and contrast DNA / RNA

Answer 9

DNA:

double stranded
ATCG
double helix
deoxyribose sugar backbone

RNA:

single stranded
AUCG
single helix
ribose sugar backbone

Question 10

describe capping

Answer 10

attached to 5’ end
protects 5’ end from degradation
facilitates transport into the cytoplasm
enhances translation

Question 11

describe polyadenylation

Answer 11

addition of many adenines 50-200

protects the 3’ end from degradation

Question 12

describe splicing

Answer 12

removal of intron and joining together of exons

Question 13

describe the triplet code

Answer 13

RNA is read in 3’s
64 possible combinations of 4 bases
codon = specific amino acid
20 amino acids
degenerate = >1 codon can code for the same amino acid
open reading frame - same nucleotide sequence can be used differently

Question 14

summarise the cell cycle

Answer 14

G0 - cell cycle arrest
G1- cellular contents, excluding the chromosomes are duplication
S- each of the 46 chromosomes is duplicated by the cell
G2- repair
mitosis - production of 4 identical daughter cells
cytokinesis - cell division