Cell Division Flashcards
(40 cards)
What are genes?
Physical units of heredity that collectively control gene transcription and therefore translation of proteins.
What are chromosomes? Where are they found
Packages of genes made of single long molecules of double stranded DNA. They are contained within the nucleus and are inherited via cell division.
What is the difference between haploid, diploid and polyploid?
Haploid (1n): each cell has 1 set of a certain number of each gene
Diploid (2n): each cell has 2 sets of a certain number of each gene
Polyploid (Xn): each cell as more than 2 sets of a certain number of each gene (inludes triploid, tetraploid, dodecaploid)
What is cytoplasmic inheritance?
The inheritance of genetic information in chloroplasts and mitochondria randomly distributed to daughter cells during cytokinesis.
What is the difference between a genotype and a phenotype?
Genotype: genetic makeup
Phenotype: observable traits controlled by alleles
What are alleles and examples?
Variations of a gene that controls outward appearance of traits. (e.g. hair colour, eye colour, etc)
What are the 3 subdisciplines of genetics?
Transmission genetics, evolutionary genetics, and molecular genetics
What is transmission genetics?
“Mendelian Genetics” that concern the transmission of traits between successive generations
What is evolutionary genetics?
Studies origins organisms, genetic relationships between organisms, and evolution of traits and genes/genomes
What is molecular genetics?
Studies inheritance and variation in nucleic acids, proteins and genomes, and connects them to variation and evolution in organisms
What are model organisms?
Species studied with the presumption that the knowledge gained can be applied to other similar organisms
What makes a god model organism?
- small size
- small genome
- large numbers of offspring
- short gestation periods
- easily accessible world wide
What are modern uses for genetics?
- Using molecular tools to understand human diseases and conditions
- DNA sequencing to identify single nucleotide polymorphisms in the genome to identify genetic disposition to inherit a disease
- GMOs, gene editing, DNA transformations
- genome-wide association studies (GWAS) to understand human evolution
What is somatic cell division?
aka mitosis, division of somatic cells to produce two identical daughter cells
What is sexual cell division?
aka meiosis, division of meiocytes in sex organs to produce unique gametes
What are the meiocytes of animals, plants, fungi, and algae?
Animals + Plants: sperm and eggs
Fungi + Algae: sexual spores
What are the stages of the cell cycle?
- M-phase: cell division
- G1: high gene expression for growth of cell
- S: synthesis phase where gene expression is paused to replicate DNA
- G2: gene expression focused on preparing for division
What is G0?
Arrest where gene expression continues but no longer progress through the cell cycle (e.g. bone, eye)
What are the 4 main checkpoints in the cell cycle?
- G1: Pass for adequate cell size, nutrient/growth factor availability
- S: Pass for completion of DNA replication and removal of errors
- G2: pass for adequate cell size for division and completion of DNA replication
- Metaphase: pass if chromosomes are attached to the mitotic spindle.
What happens in interphase?
- Chromosomes are diffuse and not visible
- Chromosomes are duplicated
- Nuclear envelope encloses nucleus
- Centrosomes are in cytoplasm
What happens in prophase?
- Chromosomes condense and become visible
- Centrosomes move toward poles
- Microtubules extend to form spindle
- Nucleolus disappears
What happens in prometaphase?
- Nuclear envelope breaks down
- Mitotic spindle attatches to kinetochores on chromatids
- Microtubules begin to push and pull chromosomes to the middle
- COHESINS bind sister chromatids together
What happens in Metaphase?
- Chromosomes fully condensed
- Chromosomes align at metaphase plate
- Chromatids are still attached to kinetochore microtubules extended from centrosomes
- Mitotic spindle is fully developed
What happens in anaphase?
- Sister chromatids separate (Disjunction) due to Cohesin break down and depolymerisation of microtubules
- daughter chromosomes move towards opposite poles
- nonkinetochore and astral microtubules polymerise and elongate the cell
