UNIT 1: Key area 3 - gene expression

Question 1

where is genetic code used and found ?

Answer 1

used in transcription and translation
found in ALL forms of life

Question 2

what is gene expression controlled by ?

Answer 2

regulation of transcription and translation

Question 3

what do genes code for ?

Answer 3

proteins

Question 4

what are proteins made of ?

Answer 4

long chains of amino acids

Question 5

what are amino acids joined together by ?

Answer 5

peptide bonds

Question 6

what shapes to proteins fold into ?

Answer 6

different shapes

Question 7

what does the shape of a protein dictate ?

Answer 7

the role it will have in cell

Question 8

where do hydrogen bonds form ?

Answer 8

between certain amino acids in a poly peptide chain

Question 9

when does a polypeptide chain becoem coiled or in a 3d shape ?

Answer 9

when hydrogen bonds are formed

Question 10

where does protein synthesis begin and end ?

Answer 10

begins in the nucleas of cell and end sun the cytoplasm

Question 11

what plays a vital role in the production of protein from the code of DNA ?

Answer 11

RNA

Question 12

compare DNA with RNA
3 points

Answer 12

1. DNA is doubke stranded whereas RNA is single stranded
2. RNA uses the base URACIL whereas DNA uses thymine
3. RNA nucleotides are similar in structure to DNA but RIBOSE replaces deoxyribose sugar

Question 13

Name the three types of RNA

Answer 13

1. messenger RNA
2. transfer RNA
3. ribosomal RNA

Question 14

explain messenger RNA (mRNA)

Answer 14

• formed in the nucleas
• carries a copy of the DNA from the nucleas to RIBOSOMES

Question 15

explain transfer RNA (tRNA)

Answer 15

molecules carry specific amino acids and bring them to ribosomes to build proteins

Question 16

explain ribosomal RNA (rRNA)

Answer 16

molecules combine with proteins to make a ribosome
ribosomal RNA is combined with proteins to form ribosomes

Question 17

where does transcription take place ?

Answer 17

nucleas

Question 18

what is transcription ?

Answer 18

the synthesis of mRNA from a section of DNA

Question 19

what is required fro transcription?

Answer 19

• RNA polymerase
• DNA template strand
• primer
• free RNA nucleotides
• ATP

Question 20

name the stages of transcription

Answer 20

1. RNA polymerase unwinds the dna strand exposing bases
2. primer attaches to complementary bases to start the mRNA chain
3. RNA polymerase adds nucleotides onto the 3 end

this is called primary transcript/mRNA

Question 21

what is RNA polymerase responsible for ?

Answer 21

this enzyme is responsible for transcription

Question 22

what does RNA polymerase molecule produce ?

Answer 22

primary transcript

Question 23

what are non coding regions called ?
where are they ?

Answer 23

IN trons they stay IN the nucleas

Question 24

what are codon regions called and where are they ?

Answer 24

EXons EXit the nucleas

Question 25

what is translation ?

Answer 25

synthesis of polypeptide protein

Question 26

where does translation occur ?

Answer 26

ribosome

Question 27

mRNA is made of sequencers of three nucleotides called ?

Answer 27

codons

Question 28

what are codons ?

Answer 28

mRNA made of sequences of three nucleotides

Question 29

what is each codon code for ?

Answer 29

one amino acid

Question 30

remaining exons are spliced together to make a continuous sequence what is this called ?

Answer 30

mature transcript

Question 31

what does each gene start and end with ?

Answer 31

start codon and stop codon

Question 32

tRNA is made of what ? and found where ?

Answer 32

a single chain of nucleotides found int he cytoplasm

Question 33

what do lomg amino acid chains make ?

Answer 33

proteins

Question 34

what are ribosomes composed from ?

Answer 34

proteins and rRNA

Question 35

steps of translation

Answer 35

1. ribosome bonds to mRNA at start codon 2. complementary anticodon carrying an amino acid attaches 3. next mRNA codon bonds with complementary anticodon 4. a peptide bond forms between 2 amino acids 5. ribosome moves one codon 6. tRNA release amino acid this can be reused 7. steps 3-6 relay until ribosome reaches stop codon

Question 36

what is alternative RNA splicing ?

Answer 36

certain conditions allow alternative segments of RNA to be treated as exons and introns

Question 37

summarise alteranative RNA splicing

Answer 37

a gene can make many differnt mature mENA transcripts therefore many different proteins

Question 38

why is tRNA folded ?

Answer 38

for atincodon site and attachment of specific amino acid