Biochemistry

Question 1

what is the purpose of the smooth endoplasmic reticulum?

Answer 1

synthesis of steroid hormones and lipids

Question 2

what is the function of the rough endoplasmic reticulum?

Answer 2

synthesis of polypeptides

Question 3

What is the purpose of the mitochondria?

Answer 3

the powerhouse of the cell via respiration (breaks down nutrients into energy)

Question 4

what is the function of the golgi apparatus?

Answer 4

to recieve materials from the ER and distribute and modify proteins

Question 5

function of ribosome?

Answer 5

to translate RNA into protein

Question 6

what are the purines?

Answer 6

adenine and guanin

Question 7

what are the pyrimidines?

Answer 7

Uracil, thymine and cytosine

Question 8

in which direction does DNA replicate in?

Answer 8

5’ to 3’ direction

Question 9

which end of the leading strand is always free?

Answer 9

3’ end

Question 10

what does helicase do?

Answer 10

unwinds DNA

Question 11

what are the three types of RNA?

Answer 11

rRNA = ribosomal
tRNA = transfer
mRNA = messenger

Question 12

what does rRNA do?

Answer 12

combine with proteins to form ribosomes where protein synthesis takes place

Question 13

what does tRNA do?

Answer 13

carries amino acids to be turned into proteins

Question 14

what does mRNA do?

Answer 14

carries genetic information for protein synthesis

Question 15

what are RNA polymerases?

Answer 15

multi-subunit complexes

Question 16

What are the three types of RNA polymerases?

Answer 16

Pol I, II, III

Question 17

what does Pol II do?

Answer 17

synthesises all mRNA

Question 18

what are the steps of transcription?

Answer 18

RNA polymerase binding by detecting initiation sites on the DNA (promoters), this requires transcription factors.
DNA chain separation.
Transcription initiation, requiring additional general transcription factors.
Elongation
Termination (release of finished RNA)

Question 19

what is TFIID?

Answer 19

a general transcription factor required for all Pol II transcribed genes

Question 20

what are exons and introns?

Answer 20

exons = coding
introns = non-coding

Question 21

what are the steps of translation?

Answer 21

anticodons of tRNA pairs with codons of mRNA.
Initiation
Elongation
Termination

Question 22

what are the components of translation?

Answer 22

amino acids, tRNAs, aminoacyl-tRNA synthetases, protein factors, ATP/GTP, ribosomes and mRNA

Question 23

describe what happens in initiation of translation?

Answer 23

GTP provides energy
robosomal subunit binds to 5’ end of mRNA, moves along until start codon found.
initiator tRNA pairs to start codon.
large subunit joins assembly and initiator tRNA is found in P site.

Question 24

where is initiator tRNA located?

Answer 24

P site

Question 25

describe what happens in elongation.

Answer 25

elongation factor brings aminoacyl-tRNA to A site. GTP input Second elongation factor regenerates the first to pick up the next aminoacyl-tRNA

Question 26

what does peptidyl transferase do?

Answer 26

catalyses peptide bond formation between amino acids in P and A sites

Question 27

describe what happens in termination in translation.

Answer 27

occurs when A site of ribosome encounters a stop codon. | finished proteins cleave off tRNA

Question 28

what are the 3 tRNA binding sites?

Answer 28

exit peptidyl aminoacyl

Question 29

where is the TATA box located?

Answer 29

about 25 nucleotides before the transcriptional start

Question 30

what is TBP and what does it do?

Answer 30

TBP = TATA box binding protein. | It recognises the TATA box

Question 31

what does TFIID do?

Answer 31

determines the transcriptional start and direction and provides a landing platform for further transcription factors and for RNA polymerase

Question 32

what does aminoacyl-tRNA synthase do?

Answer 32

binds amino acids to their corresponding tRNA molecule

Question 33

what order do the tRNA binding complexes occur in?

Answer 33

P then A then E

Question 34

free ribosomes in the cytosol are translocated____?

Answer 34

post translationally

Question 35

bound ribosomes on the rough endoplasmic reticulum are translocated ___?

Answer 35

co-translationally

Question 36

free ribosomes in cytosol make proteins for?

Answer 36

cytosol nucleus mitochondria

Question 37

bound ribosomes on the rough ER make proteins for?

Answer 37

plasma membrane ER golgi apparatus secretion

Question 38

what is Vmax?

Answer 38

maximal rate of reaction at unlimited substrate concentration

Question 39

what is Km?

Answer 39

Michaelis constant (50% of Vmax)

Question 40

Vmax is the intersection of a straight line with the __ axis.

Answer 40

Y

Question 41

Km is the intersection of the straight line with the __ axis

Answer 41

X

Question 42

What effect does a competitive enzyme have on Vmax and Km?

Answer 42

Vmax is the same | Km varies

Question 43

what effect does a non-competitive enzyme have on Vmax and Km?

Answer 43

Vmax varies | Km stays the same

Question 44

What is a primary protein characterised by?

Answer 44

a sequence of amino acids

Question 45

what is a secondary protein characterised by?

Answer 45

the formation of a backbone (polypeptide)

Question 46

what is a tertiary protein characterised by?

Answer 46

3d structure

Question 47

what is a quaternary protein characterised by?

Answer 47

spatial arrangement of multiple subunits

Question 48

which bond holds proteins together in quaternary structures?

Answer 48

disulphide bonds

Question 49

name the purines.

Answer 49

adenine and guanine

Question 50

name the pyrimidines

Answer 50

uracil, thymine and cytosine

Question 51

in which direction does DNA replicate?

Answer 51

5'-3'

Question 52

what is DNA replication catalysed by?

Answer 52

DNA polymerases

Question 53

which end is always free in the leading strand of DNA replication?

Answer 53

3' end

Question 54

what unwinds the DNA?

Answer 54

helicase

Question 55

What does RNA polymerase Pol II do?

Answer 55

synthesises all mRNA