Cell Division And Inheritance Flashcards
WHAT IS DNA
Large complex molecules which carry genetic codes that determine the characteristics of a living thing
WHAT ARE GENES
A gene is a short section of DNA. Each gene codes for a specific protein by specifying the order In which amino acids must be joined together
WHAT ARE CHROMOSOMES
The cells nucleus contains chromosomes which are made up from long DNA molecules
WHAT IS MITOSIS?
Mitosis is a type of cell division that leads occurs during growth or the repairing of damaged cells.
WHAT HAPPENS DURING MITOSIS
Two new cells are formed, which are genetically identical to the other one and the cell they were formed from
STAGES OF MITOSIS
1: parent cell
2: chromosomes make identical copies of themselves
3: they line up along the centre
4: they move apart
5: two daughter cells form with identical chromosomes to the parent cell
How many Pairs of chromosomes are in human body cells
46 chromosomes
23 pairs
One of these pairs controls the inheritance of gender
MALE CHROMOSOMES
The two sex chromosomes are different
XY
FEMALE CHROMOSOMES
The two sex chromosomes are the same
XX
WHAT ARE GAMETES
Sex cells
Male = Sperm Female = Egg
Gametes contain one set of genetic information, body cells contain 2
WHAT IS FERTILISATION?
The joining or fusion of a male and female gamete
New cell formed divided over and over by mitosis eventually forming an individual
WHAT IS DIFFERENTIATION
The process where a cell changes from one cell type to another and becomes specialised
WHERE DO HUMAN STEM CELLS COME FROM?
Human embryos
• embryonic stem cells
Adult bone marrow
• adult stem cells
WHAT IS MEIOSIS
Gametes are formed from cells in the reproductive organs by a type of cell division called meiosis.
Cells formed by meiosis have half as many chromosomes as the one they formed from
WHAT HAPPENS DURING MEIOSIS
- the chromosomes are copied
* the cell divides twice, forming four gametes
STAGES OF MEIOSIS
1: parent cell
2: chromosomes make identical copies of themselves
3: similar chromosomes pair up
4: pairs of chromosomes divide
5: chromosomes divide again into four genetically different chromosomes
WHAT IS AN ALLELE
An allele is a different form of the same gene,
For example eye colour
WHAT IS A DOMINANT ALLELE
Just one copy of a dominant gene is needed for this characteristic to develop
E.g. BROWN EYES – POLYDACTYL
Represented in CAPITALS
WHAT IS A RECESSIVE ALLELE
Both alleles must be recessive for this characteristic to develop
E.g. BLUE EYES — CYSTIC FIBROSIS
Represented in Lower case
WHAT IS A GENETIC DIAGRAM
A genetic diagram shows all the possible alleles for a particular characteristic
WHAT IS A HOMOZYGOUS ALLELE
A gene that has two identical alleles
WHAT IS HETEROZYGOUS ALLELE
A gene that has two different alleles
WHAT IS A DOUBLE HELIX?
In DNA two strands coil together to form a double helix. There are chemical cross links between the two strands formed by Pairs of bases.
DNA BASE CODE?
The protein structure is determined by the DNA base code
Proteins are made from amino acids joining together. Each amino acid I coded by the sequence of three bases
• GGT Codes are found in glycine
• TCA Codes are found in serine
WHAT IS DNA FINGERPRINTING?
By cutting a sample of DNA into fragments and comparing it with other samples it’s possible to work out if the DNA has come from the same person
WHAT IS A GENOTYPE?
The genetic makeup of an individual
For example
• the particular number of each alleles in an example
WHAT IS A PHENOTYPE
The characteristic expressed by an individual
3 ISSUES CONCERNING STEM CELLS
- some human embryos will be destroyed during the cloning process
- some think it’s miser others believe it is furthering our knowledge
- will free people from disease and suffering
