Cell Division And Inheritance Flashcards
How do body cells devide?
By mitosis
What do chromosomes contain?
The genetic information
What occurs when a body cell divides by mitosis?
Copies of the genetic material are made
Then the cell divides once to form two genetically identical body cells
When does mitosis occur?
During growth or to produce replacement cells
How many set do gametes have?
One
What are gametes?
Sex cells
How are gametes formed?
Cells in reproductive organs
Testes and ovaries in humans
Divided to form gametes, when a cell divides to form gametes:
Copies of the genetic information are made
Then the cell divides twice to form four gametes, each which a single set of chromosomes
What is meiosis?
It is the type of cell division in which a cell divides to form gametes
What happen in meiosis?
Copies of the genetic information are made
Then the cell divides twice to form four gametes, each which a single set of chromosomes
What happens when gametes join at fertilisation?
A single body cell with new pairs of chromosomes is formed. A new individual then develops by this cell repeatedly dividing by mitosis
Differentiation in plants and animals.
Most this of animals cells differentiate at an early stage whereas many plant cells retain the ability to differentiate throughout life. In mature animals, cell division is mainly restricted to repair and replacement
What are stem cells?
They are cells in human embryos and adult bone marrow
What can stem cells be used for?
Can be used made to differentiate into many differ et types of cells
e.g. nerve cells
What are human stem cells able to do?
To develop into any kind of human cell
What may treatment with stem cells be able to help with?
Conditions such as paralysis
What are the cells of the offspring produced by and what do they contain?
They are produced by asexual reproduction are produced by mitosis from the parental cells. They contain the same alleles as the parents
What does sexual reproduction give and why?
It gives variation because when gametes fuse, one of each pair of alleles comes from each parent
How many pairs of chromosomes a in the human body and how many contain the genes that determine sex?
23 pairs
One of which carries the gene that determine sex
What do female sex cells look like?
XX
What do male sex cells look like?
XY
What can some characteristic be determined by?
By a single gene
What are alleles?
Different form of the same gene
e.g. eyes have different colours
What is a dominate allele?
An allele that controls the development of a characteristics when it is presented on only one of the chromosomes
What is a recessive allele?
An allele that control the development do characterises only of the dominate allele is not present
What are chromosomes made up of?
Large molecule of DNA (A stands for acid) whichever has double helix structure
What is a gene?
A small section of DNA
What are special about genes?
Each gene codes for particular combination of amino acids which make a specific protein
What does each person have (except identical twins)?
They have a unique DNA. This can be used to identify individuals in a process know as DNA
How do you get some disorders?
They are inherited
What is polydactyly and what is it cause by?
Having extra fingers or toes
It is causes by a dominant allele of a gene and can therefore be passed on by only one parent who has the disorder
What is cystic fibrosis and how do you inherited it?
It is a disorder of cell membranes
It must by inherited by both parents. The parents may be carries of the disorder without actually having the disorder themselves. It is caused by a recessive allele of a gene and can therefore be passed on by parents, neither of whom had the disorder
What is embryo screening?
It is when an embryo is screened for the alleles that cause genetic diorders
In body cells how are chromosomes normally found?
In pairs
