DNA to Protein I Flashcards
Define gene
Section of DNA / Chromosome which codes for one or more proteins.
Some are coding and some are non - coding blocks.
Define gene expression
Genes can be switched on and off.
Genes can code for RNA too.
Define genome
An organisms entire base sequence. (found in mitochondria of every cell. )
Define exome
Part of genome which is made up of coding exons (this is the coding bit of the genome).
What are 4 main types of centromere localisations?
Metacentric = Centromere is in the middle.
Sub - Metacentric = the centromere is slightly higher than it is in metacentric formation.
Acrocentric = forms rabbit ears style formation.
Telocentric = There are no upper arms to the structure.
Which centromere localisation doesn’t exist in humans?
Telocentric
What are the 3 key features used to identify chromosomes?
1) Size
2) Banding Pattern
3) Centromere Position
What is the classic structure of ‘G - Banding’?
Classic structure of light and dark banding.
Light Band = Euchromatin
Dark Band = Heterochromatin
What do chromosomes usually exist as?
Exists as chromatin.
What happens to DNA during cell division?
DNA is complexed with various proteins and undergoes several levels of compacting via coiling and supercoiling.
What is DNA normally wrapped around?
Histones.
What is the structure of chromosome?
8 Histones
2 turns of DNA
What is the formation of nucleosome?
Octamer of Histones.
What does Histone H1 link to?
Linker DNA.
What is the difference between euchromatin and heterochromatin in terms of function?
Euchromatin allows gene expression whereas heterochromatin DOES NOT allow gene expression.
Explain heterochromatin in detail.
Inactive DNA due to NO genes present / genes aren’t expressed.
HIGHLY BOUND = No room for transcription.
Explain euchromatin in detail.
Actively expressed DNA.
LOOSELY BOUND = Allows room for transcription.
What is the function of centromeres?
Keeps sister chromatids together.
Attaches to microtubules during cell division.
Structurally intergral.
What is the effect of having heterochromatin in the centromere structure?
Normally highly repetitive.
What is the function of telomerase?
Repairs telomeres but is only ACTIVE in certain cell types.
= Can lead to cancer if switched on in the wrong cells.
What happens to the structure of telomeres when they degrade?
They become shorter and thus, can affect the gene function and protein production.
What are the stages in the cell cycle?
G0 G1 S G2 Mitosis Cytokinesis
What happens in G1?
Cell makes a variety of proteins which are needed for DNA replication. (known as a single chromatid).
What happens in G0?
Cell cycle arrest occurs.