Storing and using genetic information Flashcards
What is DNA?
chain of nucleotide monomers
What does a nucleotide consist of?
sugar
base
phosphate group
How many hydrogen bonds for Gs and Cs?
3
How many hydrogen bonds for As and Ts?
2
What is chromatin at the simplest level?
double stranded helical structure of DNA
What is a nucleosome?
each nucleosome consists of eight histone proteins around which the DNA wraps around1.65 times
What is a chromatosome?
consists of a nucleosome plus the H1 histone
What is chromatin?
chromatin is the name given to the mixture of DNA, proteins and RNA that package DNA within the nucleus
What are the two forms of chromatin?
heterochromatin- packaged and darker regions of chromosome
euchromatic- extended, region where the genes tend to be more active and turned on
What are the two major mechanisms by which chromatin is made more accessible?
histones can be enzymatically modified
histones can be displaced by chromatin remodeling complexes.
These processes are reversible
Describe what is meant by DNA replication being semi conservative?
one half of each new molecule of DNA is old, one half is new
Describe the process of DNA replication?
special proteins unzip the double helix by breaking the hydrogen bonds
new nucleotide molecules are then paired with the two DNA strands
replicated in 5’ to 3’ direction
What percentage of bases is the same in all humans?
99.9%
What is a set of 3 bases called?
codon
Describe redundancy of genetic code?
you can get changes or mutations in protein sequence and it doesn’t impact it.
What is the change in AA in sickle cell anaemia?
Glu substituted by Val (hydrophobic).
(GAA or GAG becomes GUA or GUG)
How does substitution lead to sickle cell anaemia?
causes haemoglobin which would normally be free floating around in the the cytoplasm to form very long chains of haemoglobin.
Makes the cell the completely wrong shape for efficient oxygen transport.
And cannot flow through the blood vessels as easily and will often form blood clots and blockages in vessels
What is transcription?
so encoding the sequence in DNA into RNA
What is translation?
takes the RNA sequence and converts it into a polypeptide
What does alternative splicing mean?
from one gene , can have multiple variants of mRNA
Describe the process from nucleus to protein?
nucleus : containing all genetic info
genetic info being transcribed into mRNA
mRNA is then alternatively spliced to give individual proteins that have different functions
Processed RNA leaves nucleus and using tRNA and rRNA to produce protein
At ribosome , protein has multiple modifications
What is role of tRNA?
Major role is to translate mRNA sequence into amino acid sequence.
Acts as an adapter molecule between the coded amino acid and the mRNA
What is rRNA?
Component of ribosomes.
rRNA molecules are produced in the nucleus
Transported to cytoplasm, where they combine with proteins to form a ribosome.
