Usin Genetics & storing it Flashcards
Phenotype?
Outward physical manisfestation of organisms genes
Genotype?
Full hereditary info of organism (even if not expressed)
Whats the difference between 2’-deoxyribose sugar & a ribose sugar?
On carbon 2 ribose has a hydroxyl group
On carbon 2 deoxyribose sugar has just a hydrogen
Which way is the twist of the DNA double helix?
Right hand (to the right)
How many H bonds join Cytosine & guanine?
3 H bonds between cytosine & guanine
How many H bonds between adenine & thymine?
2 H bonds between thymine & adenine
same for Adenine-Uracil
DNA is coiled around what protective protein?
Histones
What is DNA called when wrapped round a histone?
A nucleosome
List the stages of DNA packaging from smalledst to largest:
DNA
- > Nucleosome
- > Coils
- > Supercoils
- > Chromosome
At what point do the supercoils form chromosomes?
Just before cell division occurs
What makes up chromatin?
The DNA, proteins & RNA that packages DNA within the nucleus
What are the 2 forms of chromatin?
Heterochromatic (condensed) form
Euchromatic (extended) form
Why must the double helix strands seperate during transcription & replication?
To remove the histone & folding barriers so enzymes have access to the DNA
In what two ways is the chromatin made more accessible to enzymes? (regarding histones)
By enzymatically modifying the histones or by displacing them with chromatin remodelling complexes.
Both are reversible
How many new DNA molecules are made in replication?
2
What does semi-conservative replication mean?
It means each of the 2 new DNA molecules contains 1 strand from the original & 1 new strand.
In what direciton is the DNA replicated?
From 5 prime end to the 3 prime end.
5’ to 3’
Why is DNA replication bi-direcitonal?
Because the DNA are anti-parallel, i.e. their prime ends are in reverse to eachother.
So ones built upward & one downward
Which DNA template strand is the lagging & which the leading?
The laggine strand is the one trying to build in the opposite direction to the unzipping
The leading is the one building DNA in the same direction as the unzippin
What are okazaki fragments?
Pieces of new DNA being made on the lagging template that will join together at the end.
What are hte coding sections of DNA called?
Exons
What are the ‘junk’ sections of DNA called?
Introns
What do you call teh process of making mRNA?
TRanscription
How is mRNA different to the DNA?
mRNA only uses the exons, stiching them together without hte introns in between
What is the redundancy or degeneracy of the genetic code?
degeneracy refers to the fact that often the last base of a codon can be canged without changin the amino acid produced.
What mutation caues sickle cell anemia?
Hydrophilic Glutamate is replaced by hydrophobic Valine in the haemoglobin gene
Why has sickle cell anemia survived in the tropics?
It has a selective advantage of making you immune to malaria.
What does mRNA do?
Carries exon info from DNA in nucleus to the cytoplasm
People have many more proteins than genes, how can 1 gene produce multople proteins?
mRNA can be alternatively spliced to contain only some of the exons in a gene, giving many more options for DNA amino acid arrangment
What are different proteins from the same gene called?
Protein Isoforms
In what process is tRNA involved?
tRNA is involved in translation of mRNA into an amino acid sequence
What does tRNA do specifically?
Acts as an adapter molecule between coded amino acid & mRNA. It brings the amino acid & joins it to the growing polypeptide chain
What is rRNA?
A component of ribosomes
What is a polysome?
A collection of ribosomes simultaneously translate one section of mRNA
How do tRNA molecules reconise part of the mRNA chain?
tRNA molecules contain anticodons allowing them to match up to the right section of mRNA & amino acid.
