Life Processes And Cellular Level Flashcards
(22 cards)
Meiosis
Function: used for the production of sex cells (gametes)
- Egg and sperm
How many daughter cells do Meiosis produce
Meiosis produces 4 daughter cells which have half (haploid) number of chromosomes to parent cells
Daughter cells are NOT identical to the parent cell
The two stages of meiosis
Meiosis 1: homologous chromosomes pair up on the equator
Meiosis 2: very similar to mitosis
PMAT
- Phrophase
- Metophase
- Anaphase
- Telophase
Gametes
Sex cells (in animals eggs and sperm cells)
Homologous chromosomes
A pair of chromosomes (one maternal and one paternal) Which contains the same genes and pairing up during meiosis
Haploid
Means half the number of chromosomes e.g gametes are haploid cells (n) in humans haploid number is 23
Diploid
Cells containing two sets of chromosomes (2n) in humans the diploid number is 46
Somatic cells
Body cells
Independent assortment
Each chromosome pair is sorted independently of the other pairs when thy line up at the equator. The process is random and results in huge variety of gametes as maternal and paternal chromosomes aren’t necessarily on the same side
Crossing over
When homologous chromosomes pair up in meiosis. 1 it is possible for genes to be exchanged between the two chromosomes
Gene
Section of DNA which code for a specific protein
Allele
Alternate form of a gene (different kinds)
E.g eye colour brown, blue, green
Gene pool
The genes present an interbreeding population
Population
A group of individuals of the same species living in the same area at the same time
What is genetic variation
The diversity of alleles and genes between individuals or within a population
Mutations
Considered to be the “ultimate source of genetic variation”
A mutation is the only way new genetic information can be added to a gene pool
Mitosis
Production of somatic cells for growth and repair (2 identical daughter cells with same number of chromosomes as the parent)
Genotype
Genetic make up of an individual e.g Bb
Phenotype
Physical expression of genes e.g brown eyes
What you see on the outside
Crossing over description
Each homologous pair of chromosomes have a paternal and maternal chromosomes which contain the same genes (but potentially different alleles)
In prophase the homologous chromosomes pair up and become very close
This pairing allows a chiasma (joint) to form between chromatids and genes are exchanged
When chromosomes separate each of the chromosomes will have a new genetic material
Segregation
Every individual contains a pair of alleles for each particular trait which segregate
(Separate) during meiosis
