Chromosomes, Cell Division, Meiosis and Chromosome Abnormalities Flashcards
What are the 3 features of chromosome structure?
Telomere
Centromere
Heterochromatin/Euchromatin
DNA replication is symmetric/asymmetric?
Asymmetric.
What happens when DNA polymerase binds to the next Okazaki fragment on the lagging strand?
Bind fragments together with DNA ligase.
What is needed to start every replication including individual fragments?
RNA primer sequence.
What problem does RNA primer sequence have for the last part of DNA to be replicated?
End-replication problem. Can start to decay.
What can bind to the end of DNA to stop it’s problem?
Telomerase enzyme which adds DNA using an RNA template.
What are the 4 stages of cell cycle and division?
G1
S
G2
M
What happens during prophase?
Chromosomes condense
Nuclear membrane disappears
Spindle fibres form from centriole
What happens during metaphase?
Chromosomes align at equator
Attach by fibre to centriole
Max condensation of chromosome
What happens during anaphase?
Sister chromatids separate longitudinally
Move to opposite ends of cell
What happens during telophase?
New nuclear membrane forms
Each cells contains 46 chromosomes
What happens during cytokinesis?
Cytoplasm separates
Two new daughter cells.
What are centromeres the site of?
Kinetochore
What is a kinetochore?
Protein complex that binds to microtubules.
Heterochromatin are ______ genes and euchromatin are ______ genes.
Silenced
Active
What are the two types of tandemly repeated DNA sequences?
Satellite
Microsatellite
What are the 2 types of highly repeated interspersed DNA sequences?
SINE
LINE
DNA is packaged with histone proteins to form what?
Chromatin
What charge do DNA and histone proteins have?
DNA is negative and histone proteins are positive.
What is a nucleosome?
DNA wrapped 2 around core of 8 histone proteins.
How many nucleosomes are in each turn?
6
What is the process of condensing chromatin?
Nucleosome
Chromatin fibre
Fibre-scaffold complex
Chromosome
What are the 3 reasons for packaging DNA?
Uses less space
Neutralised DNA
Inactive DNA folded until required.
What is the process of chromosome analysis?
Blood Separate red cells Incubate white cells Add colchicine Separate white cells Add hypotonic saline Fix cells to spread Stain Photograph Karyotype
What is colchicine?
Microtubule inhibitor
What are metacentric karyotypes?
Centromere very central
What are submetacentric karyotypes?
Centromere less central
What are acrocentric karyotypes?
Centromere no where near central.
What does FISH stand for?
Fluorescent in situ hybridisation
What are the 4 types of FISH probes?
Unique
Centromeric
Telomeric
Whole chromosome
What does meiosis do to diploid cells?
Half them to haploid.
What happens to chromosomes in meiosis?
Passed on as recombined copies creating genetic variation.
How many cycles occur in one meiosis?
2
What are the 4 steps of meiosis?
Prophase
Metaphase
Anaphase
Telophase
What is oogenesis?
Process of egg formation
What is spermatogenesis?
Process of sperm formation.
When do sperm go through their 2nd meiosis cycle?
Puberty
When do ovules go through their 2nd meiosis cycle?
Ovulation
Where do mitochondria only come from?
Mother via egg.
What is x-inactivation?
Random inactivation of one X chromosome in females.
