Midterm Flashcards
G1 phase
Growth and cellular metabolism
S phase (synthesis)
DNA replication, chromosomes duplication
G2 phase
Prepare for mitosis
M phase
Mitosis
Interphase
Time between successive mitosis’s (G1+G2+S)
G0 phase
Terminal event. eg. neutrons with axons and dendrites
Why does mitosis happen
Growth, cell replacement, healing, reproduction
Prophase
Chromosomes condense, centrosomes produce microtubules and migrate to opposite poles
Pro metaphase
Microtubules attach to chromosomes and nuclear envelope begins to break down
Metaphase
Chromosomes align in centre of cell
Anaphase
Sister chromatids migrate to opposite poles
Telophase
Nuclear envelope begins to reform, chromosomes condense
meiosis I
Randomly separates chromosomes
meiosis II
Separates sister chromatids like mitosis
M cyclin
CDK helps prepare the cell for mitosis
S cyclin
CDK helps initiate DNA synthesis
G1/ S cyclin complex
Prepares the cell for DNA replication
DNA replication checkpint
Checks for any un-replicated DNA at the end of g2 phase (before cell enters mitosis)
Cell cycle check points
Cell replication pauses to make sure it is okay for the cell to go on to the next stage. There are specialized CDK complexes to do so
DNA damage checkpoint
Checks for damaged DNA before the cell enters S phase, makes sure genes that inhibit the cell cycle are turned off
Spindle assembly checkpoint
Checks that all chromosomes are attached to spindle fibres, after DNA replication checkpoint
Oncogene
Cancer causing gene
Proto- oncogene
Normal genes important for promoting cell division, but have the potential to become cancerous if mutated
Tumour suppressors
genes that encode proteins whose normal activity inhibits cell division
Cancer development
Normal cells: Inactivation of the first tumour suppressor gene
benign cancer: Activation of the oncogene
Malignant/ metastatic cancer : Inactivation of the second and third tumour suppressor gene
Principle of dominance
In a heterozygote, one allele may conceal the presence of another
Principle of segregation
In a heterozygote, two alleles R and r separate themselves in the form of gametes
Principle of independent assortment
Alleles on different parts of chromosomes assort independently from one another (in anaphase I)
Addition
OR
Multiplicative
AND
Monogenic trait
When one gene is responsible for one trait
Polygenic trait
There are multiple genes responsible for a person’s height
Prophase I
Synapse (gene-for-gene pairing)
Bivalent (crossing over)
Chromosomes condense and nuclear envelope begins to break down
Prometaphase I
Spindles attach to kinetochores on chromosomes
Metaphase I
Mono orientation
Anaphase I
Homologous chromosomes separate but sister chromatids do not
Telophase and cytokinesis (meiosis I)
Cells go from diploid to haploid
Prophase II
Nuclear envelope breaks down and chromosomes condense
Pro metaphase II
Spindles attach to the kinetochores on chromosomes
Metaphase II
Chromosomes align in the centre of the cell
Anaphase II
Sister chromatids separate, replication in policy has already happened
Telophase and cytokinesis (meiosis II)
Cytoplasm does not divide equally
Males: Each n cell is a sperm cell
Females: 3 polar bodies and 1 oocyte (egg)
Pedigree of autosomal dominant traits
Equal in males and females
Does not skip generations
Affected offspring will have an affected parent (unless they posses a new mutation)
Pedigree characteristics of autosomal recessive traits
Equal in both sexes
Skips generations
Affected can be born to unaffected children
Appears more frequently among children of consanguineous marriages
Human sex chromosomes
There is a small region of homology where pairing occurs
Y chromosome is our smallest chromosomes
They are not similar enough for any crossing over to happen