Large molecules which carry the genetic code that determines the characteristics of a living thing.
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What is a gene?
A small section of DNA which codes a specific protein and specifies the order in which amino acids should join
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What are chormosomes?
Are made up of DNA and are found in the nucleus of a cell.
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What is mitosis?
When a body cell divides into two identical cells
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Describe the process of mitosis.
1. A copy of each chromosome ismade before the cell divides. 2. The cell divides once 3. Two identical cells are formed.
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What are unspecialised cells called?
Stem cells
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When would mitosis occur?
Repair and replacement or asexual reproduction (no variation)
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What are the key features of asexual reproduction?
Produced from a parent cell. Contain the same alleles as the parents which means there is no variation.
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What is Meiosis?
The division of ells in reproductive organs to make gametes.
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What are gametes?
They are sex cells. The female gamete is the ova and the male gamete is the sperm
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How many chromosomes does a human cell have?
23 pairs - 46 in total
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How many chromosomes do gametes have?
23
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Why does sexual reproduction result in variation?
The gametes from each parent fuse which result to half the genetic information coming from the father and half from the mother.
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When two gametes fuse together, what cell division takes place afterwards?
Mitosis
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Describe the process of meiosis?
1. A copy of a each chromosome is made in the nucleus 2. The cell divides TWICE 3. 4 gametes are produced as a result with a different combination of genes.
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What are stem cells?
Unspecialised cells
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What do stem cells do?
They have the ability to differentiate into types of body cells for example nerve cells.
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Where are stem cells found?
IN human embryo and bone marrow
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How can stem cells be used for medical use?
It is hopes that stem cells will be able to into many types of cells which can then be used to treat conditions such as paralysis.
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Who is Gregor Mendel?
Mendel was a monk who worked out how characteristics were inherited
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What are alleles?
Different versions of the same gene.
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What is a dominant allele?
1 copy of the allele is needed for you to see it in the phenotype
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What is a recessive allele?
2 copies of the allele need to be present in order for you to see it in the phenotype.
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Define Phenotype?
An observable or measurable characteristic ( Physical appearance)
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What is a Genotype?
The combination of the alleles which create the genetic make up of an individual
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Define Homozygous
Both of the alleles are the same (DD - homozygous dominant) (dd - Homozygous recessive)
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Give an example of an dominant disease
Huntington Disease and Polydactyly
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How many alleles must an offspring inherit in order to get a dominant disease?
Just one dominant allele form a parent.
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Give an example of an recessive disease
Cystic Fibrosis
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How many alleles must an offspring get in order to get the disease?
Two recessive alleles
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If a parent has an allele of a disease what are the also known as?
Carriers
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Define Heteroygous
When two alleles are different (e.g Dd)
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What can be used to show the possibility of inheriting a disease?
A punnet square
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Other cards in this set
Card 2
Front
What is DNA?
Back
Large molecules which carry the genetic code that determines the characteristics of a living thing.
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