B12 Reproduction Flashcards
What happens in stage 1 of cell cycle
Chromosones replicate and number sub cellular structures increase
What happens during stage 2 of the cell cycle
Mitosis- One set of cheomosones is pulled to each end of the cell
What happens during stage 3 of the cell cycle
Cytokinesis- the cytoplasm and cell membrane devides into two identical daughter cells
Give 4 ways sperm cells are adapted for their function
Has a tail- helps it move to the egg
Contains genetic information
Contains lots of mitochondria- to transfer the energy needed foe the tail to work
Contains many enzymes- allow sperm to break through egg membranes
Give 4 features of sexual reproduction
Involves two parents
Involves gametes
There is variation in the offspring
Genetic material is mixed
How many pairs of chromosones do human body cells have
23 pairs in the nucleus
What is the genome of an organism
The entire genetic material of the organism
How many chromosones do egg and sperm cells contain
23 chromosones
How many chromosones does a fertalised egg contain
46 chromosnes
What is a dominant allele
An allele that controls a characteristic when it is present e.g BB or Bb
What is a recessive allele
An allele that controls the characteristic when a dominant allele isn’t present e.g. bb
How many chromosones are there in human body cells, how are they aranged?
46 chromosnes arranged in pairs
Why do sex cells have half the usual number of chrmosones
So when they fertalise they restore 46 chromosones
What happens to the chromosne number at fertalisation
It doubles
What is an allele
A different version of a gene
What is homozygote
Two identical alleles for a characteristics
What is heterozygote
Different alleles for a characteristic
What is genotype
Describes the alleles present of an individual regarding a particular characteristic e.g Bb or bb
What is phenotype
Describes the physical appearance of an individual regarding a particular characteristic e.g black fur
What is a gene
A small section of DNA found in a chromosone
What is genome
Entire set of genetic material in an organism
What are chromosones
Long molecules of DNA
What are gametes
Contaims half the normal amount of chromosones in a cell (23) as it only has on eof each chromosone
What gender is X sperm and Y sperm
X sperm is a girl
Y sperm is a boy
