Cell division and growth B2 5.1+5.2 Flashcards
Human chromosomes are usually found in pair (except for in sex cells). How many pair of choromosomes are there in each body cell?
23
What do chromosomes contain?
Genetic information
What is mitosis?
The process which body cells divide.
2 genetically identical body cells are formed from the original cell.
What happens to a body cells when mitosis occur?
- Copies of the genetic material are made
- Then the cell divides once to form two
genetically identical body cells.
What are alleles?
Some characteristics are controlled by a single
gene. Each gene may have different forms
called alleles.
How is genetic material copied in mitosis?
A copy of each choromosome (containing alleles) is made before the cell divides.
Why is mitosis necessary?
- growth
- to produce replacement cells for the repair of damaged tissues.
What are sex cells also called?
Gametes.
What is the difference between body cells and sex cells?
Body cells have two sets of chromosomes;
gametes have only one set.
What is meiosis?
The type of cell division which
cells in reproductive organs ( testes and ovaries in
humans )
divide to form gametes
What are the reproductive organs in human?
Testes and ovaries
What are human gametes?
Sperm and ova
What happens when a cell divides to form gametes?
- Copies of genetic information are made
2. The cells divded twice to form four gametes, each with a single set of chromosomes.
How is a new individual formed?
Gametes join at fertilisation
A single body cell with new pairs of chromosomes formed
A new individual then develops by this cell repeatedly dividing by mitosis.
When do animal cells and plant cells differentiate?
Animal cells differentiate early stage
Many plant cells retain the ability to
differentiate throughout life.
What is the role of cell division in mature animal?
restricted to replacement and repair.
What are stem cells and where are they found?
Unspecialised cells.
Human embryo and adult bone marrow.
What can human do with stem cells?
Make them differentiate into
many different types of cells, eg nerve cells.
What are the cells of the offspring produced by asexual
reproduction, produced by?
Mitosis from the parental cells.
They contain the same alleles as the parents.
