Gene-nutrient interactions - macro and micro Flashcards
In the cell, what is the function of the plasma membrane?
segregates cell from environment
In the cell, what is the function of the genome?
codes for all cellular structures
In the cell, what is the “information transfer”?
expresses information stored in genetic code
In the cell, what is the “energy utilisation”?
harness energy to build more complex components
In the cell, what is the function of the nucleus?
gene expression, proteins exported and imported, RNA exported
In the cell, what is the function of the ER?
protein modification, proteins imported cotranslationally
In the cell, what is the function of the golgi apparatus?
protein modification, proteins arrive by trafficking from ER
In the cell, what is the function of the endosome?
early = sort internalised proteins for transport to other compartments
late = proteins that function in endosomes are targeted from secretory pathway
In the cell, what is the function of the lysosome?
degradation of internalise proteins, degradation of cystolic proteins in stressed cells, proteins that function in lysosomes are targeted from the trans-golgi network
In the cell, what is the function of the mitochondrion?
energy handling, proteins imported from cytosol, some proteins synthesised in organelle
In the cell, what is the function of the peroxisome?
oxidative processes, protein imported from cytosol
What does the control of cell function require?
co-factors (water, ions, vitamins, etc)
What does the structure of cell function require?
involves lipids, carbohydrates
Structure and function of cell can be altered by?
exogenous compounds (therapeutic or toxic)
Which part does the nitrogen interact with on the sugar?
hydroxyl group
Name the pyrimidine bases:
cytosine (3H bond) and thymine (2H bond)
name the purine bases:
adenine (2H bond) and guanine (3H bond)
What is Chargaff’s rule?
the content of A equals the content of T, the content of T equals content of C… in double-stranded DNA from any species
What is the charge of supercoiled DNA?
negative
Name the general organisation of DNA:
- nucleosome
- chromatin
- chromosome
List the structure from double helix DNA to chromosome:
- 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
How is DNA synthesised?
- unwind DNA in two strands
- both used by polymerase to make complimentary new strand = two daughter strands
What are Okazaki fragments?
synthesised discontinuously in short 5’-3’ fragments
When is DNA synthesis initiated?
3’-oh of primer mediates the nucleophilic attack of alpha-phosphate of the incoming dNTP
What are the 3 processes responsible for gene expression?
- transcription
- RNA processing
- Translation (protein synthesis)
In what way is RNA different from DNA?
- 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
What is the process of transcription of DNA into RNA (simplified version)?
- 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’
What are important differences in transcription of RNA, compared to DNA?
- 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)
What 2 things direct location on DNA template where RNA polymerase begins and ends transcription?
promoters and terminators
what are the 4 phases of transcription of DNA into RNA?
- promoter recognition
- initiation
- elongation
- termination
What 4 things control mRNA expression?
- transcription factors
- enhancers
- co-activators
- co-repressors
What happens in the mRNA synthesis, under the splicing process?
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
