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Principles Em > Biochemistry > Flashcards

Biochemistry Flashcards

1
Q

what is the purpose of the smooth endoplasmic reticulum?

A

synthesis of steroid hormones and lipids

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2
Q

what is the function of the rough endoplasmic reticulum?

A

synthesis of polypeptides

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3
Q

What is the purpose of the mitochondria?

A

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

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4
Q

what is the function of the golgi apparatus?

A

to recieve materials from the ER and distribute and modify proteins

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5
Q

function of ribosome?

A

to translate RNA into protein

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6
Q

what are the purines?

A

adenine and guanin

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7
Q

what are the pyrimidines?

A

Uracil, thymine and cytosine

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8
Q

in which direction does DNA replicate in?

A

5’ to 3’ direction

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9
Q

which end of the leading strand is always free?

A

3’ end

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10
Q

what does helicase do?

A

unwinds DNA

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11
Q

what are the three types of RNA?

A 
rRNA = ribosomal
tRNA = transfer
mRNA = messenger
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12
Q

what does rRNA do?

A

combine with proteins to form ribosomes where protein synthesis takes place

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13
Q

what does tRNA do?

A

carries amino acids to be turned into proteins

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14
Q

what does mRNA do?

A

carries genetic information for protein synthesis

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15
Q

what are RNA polymerases?

A

multi-subunit complexes

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16
Q

What are the three types of RNA polymerases?

A

Pol I, II, III

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17
Q

what does Pol II do?

A

synthesises all mRNA

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18
Q

what are the steps of transcription?

A

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)

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19
Q

what is TFIID?

A

a general transcription factor required for all Pol II transcribed genes

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20
Q

what are exons and introns?

A 
exons = coding
introns = non-coding
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21
Q

what are the steps of translation?

A

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

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22
Q

what are the components of translation?

A

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

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23
Q

describe what happens in initiation of translation?

A

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.

24
Q

where is initiator tRNA located?

A

P site

25
Q

describe what happens in elongation.

A

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

26
Q

what does peptidyl transferase do?

A

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

27
Q

describe what happens in termination in translation.

A

occurs when A site of ribosome encounters a stop codon.

finished proteins cleave off tRNA

28
Q

what are the 3 tRNA binding sites?

A

exit
peptidyl
aminoacyl

29
Q

where is the TATA box located?

A

about 25 nucleotides before the transcriptional start

30
Q

what is TBP and what does it do?

A

TBP = TATA box binding protein.

It recognises the TATA box

31
Q

what does TFIID do?

A

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

32
Q

what does aminoacyl-tRNA synthase do?

A

binds amino acids to their corresponding tRNA molecule

33
Q

what order do the tRNA binding complexes occur in?

A

P then A then E

34
Q

free ribosomes in the cytosol are translocated____?

A

post translationally

35
Q

bound ribosomes on the rough endoplasmic reticulum are translocated ___?

A

co-translationally

36
Q

free ribosomes in cytosol make proteins for?

A

cytosol
nucleus
mitochondria

37
Q

bound ribosomes on the rough ER make proteins for?

A

plasma membrane
ER
golgi apparatus
secretion

38
Q

what is Vmax?

A

maximal rate of reaction at unlimited substrate concentration

39
Q

what is Km?

A

Michaelis constant (50% of Vmax)

40
Q

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

A

Y

41
Q

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

A

X

42
Q

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

A

Vmax is the same

Km varies

43
Q

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

A

Vmax varies

Km stays the same

44
Q

What is a primary protein characterised by?

A

a sequence of amino acids

45
Q

what is a secondary protein characterised by?

A

the formation of a backbone (polypeptide)

46
Q

what is a tertiary protein characterised by?

A

3d structure

47
Q

what is a quaternary protein characterised by?

A

spatial arrangement of multiple subunits

48
Q

which bond holds proteins together in quaternary structures?

A

disulphide bonds

49
Q

name the purines.

A

adenine and guanine

50
Q

name the pyrimidines

A

uracil, thymine and cytosine

51
Q

in which direction does DNA replicate?

A

5’-3’

52
Q

what is DNA replication catalysed by?

A

DNA polymerases

53
Q

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

A

3’ end

54
Q

what unwinds the DNA?

A

helicase

55
Q

What does RNA polymerase Pol II do?

A

synthesises all mRNA

Principles Em (10 decks)

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