Molecular basis of genetics Flashcards
Karyotype
ordered display of chromosomes
Telomeres
The ends of a chromosome
Kinetochore
The part of the chromosome that the spindle fibres attach to during metaphase
What are the 5 stages of Mitosis?
Prophase, Prometaphase, Metaphase, Anaphase, Telophase
What is the role of the centromere?
To act as a site of assembly of the kinetochore
What are the differences between RNA and DNA
can exist as either single or double stranded, has uracil instead of Thymine and a hydroxyl group on C2 making it more reactive and susceptible to degradation
What bonds link nucleotides together?
Phosphodiester bonds
Histone
A protein that associates DNA in the nucleus and helps condense DNA into a smaller volume
Chromatin
a complex of DNA and proteins that forms chromosomes within the nucleus of eukaryotic cells
Euchromatin
less condensed and can be transcribed
Heterochromatin
more condensed and typically not transcribed
Nucleosome
The subunit of chromatin
Histone octamer
8 histone proteins
What is the charge of histone proteins?
Positive (made up of positive amino acids)
Linker DNA
links two nucleosomes together
Chromatin remodelling
When a cells chromatin ‘opens up’ to allow gene expression to take place
ATP dependent chromatin remodelling
complexes restructures the nucleosome- requires energy
Why do we need to control how DNA is used?
Different cells have different functions, an animal has different needs throughout their life and they need to adapt to their environment
What are some examples of histone modification enzymes?
acetyl transferases, methyl transferases, kinases
What does acetylation do?
activates the gene
What does methylation do?
inactivates the chromatin
epigenetics
inherited traits that do not represent a change in genetic information
What are some amino acids with positive charges?
Lysine, Arginine
What is mitosis?
When a cell splits into two genetically identical daughter cells
where is histone H1 located?
in the nucleosome linker DNA
What proteins are found in the nucleosome?
two copies of each of H2A, H2B H3 and H4
What is a fibre formed from?
Nucleosomes folded around each other
Which histone protein does fibre formation require?
H1
What are chromatin fibres folded into?
loops
what does HAT do?
removes the positive charge from lysine therefore making the histone neutral so it has less affinity for the sugar phosphate backbone
What is the charge of a histone protein?
positive
How long is each base pair?
around 0.34 nanometres long
What is the unit of genetics?
The gene (length of DNA that contains the instructions to produce RNA and therefore a protein)
Chromatosome
when linker DNA binds nucleosomes together
What is the physical role of the centromere?
To act as a site of assembly for the kinetochore
