Gene-nutrient interactions - macro and micro

Question 1

In the cell, what is the function of the plasma membrane?

Answer 1

segregates cell from environment

Question 2

In the cell, what is the function of the genome?

Answer 2

codes for all cellular structures

Question 3

In the cell, what is the “information transfer”?

Answer 3

expresses information stored in genetic code

Question 4

In the cell, what is the “energy utilisation”?

Answer 4

harness energy to build more complex components

Question 5

In the cell, what is the function of the nucleus?

Answer 5

gene expression, proteins exported and imported, RNA exported

Question 6

In the cell, what is the function of the ER?

Answer 6

protein modification, proteins imported cotranslationally

Question 7

In the cell, what is the function of the golgi apparatus?

Answer 7

protein modification, proteins arrive by trafficking from ER

Question 8

In the cell, what is the function of the endosome?

Answer 8

early = sort internalised proteins for transport to other compartments

late = proteins that function in endosomes are targeted from secretory pathway

Question 9

In the cell, what is the function of the lysosome?

Answer 9

degradation of internalise proteins, degradation of cystolic proteins in stressed cells, proteins that function in lysosomes are targeted from the trans-golgi network

Question 10

In the cell, what is the function of the mitochondrion?

Answer 10

energy handling, proteins imported from cytosol, some proteins synthesised in organelle

Question 11

In the cell, what is the function of the peroxisome?

Answer 11

oxidative processes, protein imported from cytosol

Question 12

What does the control of cell function require?

Answer 12

co-factors (water, ions, vitamins, etc)

Question 13

What does the structure of cell function require?

Answer 13

involves lipids, carbohydrates

Question 14

Structure and function of cell can be altered by?

Answer 14

exogenous compounds (therapeutic or toxic)

Question 15

Which part does the nitrogen interact with on the sugar?

Answer 15

hydroxyl group

Question 16

Name the pyrimidine bases:

Answer 16

cytosine (3H bond) and thymine (2H bond)

Question 17

name the purine bases:

Answer 17

adenine (2H bond) and guanine (3H bond)

Question 18

What is Chargaff’s rule?

Answer 18

the content of A equals the content of T, the content of T equals content of C… in double-stranded DNA from any species

Question 19

What is the charge of supercoiled DNA?

Answer 19

negative

Question 20

Name the general organisation of DNA:

Answer 20

• nucleosome
• chromatin
• chromosome

Question 21

List the structure from double helix DNA to chromosome:

Answer 21

• short region of DNA double helix
• ‘beads-on-a-string’ form of chromatin
• chromatin fibre of packed nucleosomes
• condensed metaphase chromosome in coils
• into X structure of metaphase chromosome

Question 22

How is DNA synthesised?

Answer 22

• unwind DNA in two strands

- both used by polymerase to make complimentary new strand = two daughter strands

Question 23

What are Okazaki fragments?

Answer 23

synthesised discontinuously in short 5’-3’ fragments

Question 24

When is DNA synthesis initiated?

Answer 24

3’-oh of primer mediates the nucleophilic attack of alpha-phosphate of the incoming dNTP

Question 25

What are the 3 processes responsible for gene expression?

Answer 25

• transcription
• RNA processing
• Translation (protein synthesis)

Question 26

In what way is RNA different from DNA?

Answer 26

• minor modification of the sugar component = DNA is deoxyribose and RNA is ribose
• RNA contains NO thymine, but it’s uracil
• RNA is found in the cell as a single stranded molecule

Question 27

What is the process of transcription of DNA into RNA (simplified version)?

Answer 27

• DNA double helix unwound and RNA strang is built on template strand
• RNA transcript dissociates from DNA template a few nucleotides behind the point of synthesis
• DNA strands reanneal
• transcription is from 5’ to 3’

Question 28

What are important differences in transcription of RNA, compared to DNA?

Answer 28

• new strand made from ribonucleotides (not deoxyribonu.)
• RNA polymerase, and doesn’t need primer, transcribe de novo
• RNA product does not remain base-paried to DNA template strand
• multiple RNA polymerase can transcribe same gene at same time
• large number of transcripts in short time
• then the two DNA strands reanneal after RNA product dissociates
• transcription is less accurate than replication (no extensive proof reading)

Question 29

What 2 things direct location on DNA template where RNA polymerase begins and ends transcription?

Answer 29

promoters and terminators

Question 30

what are the 4 phases of transcription of DNA into RNA?

Answer 30

• promoter recognition
• initiation
• elongation
• termination

Question 31

What 4 things control mRNA expression?

Answer 31

• transcription factors
• enhancers
• co-activators
• co-repressors

Question 32

What happens in the mRNA synthesis, under the splicing process?

Answer 32

0 primary transcript combines with snRNPs to form spliceosome

• 2’-OH of branch site attacks the 55’-p at the splice donor site of intron, forming a 2’-5’ phosphodiester bond and a lariat
• free 3’-OH of exon 1 then attacks the 5’-p at the splice acceptor site, forming phosphodiester bond that joins exon 1 and 2