Simple Inheritance in Animals and Plants - B2
- Created by: chickpeatweet
- Created on: 17-04-14 11:49
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- Simple Inheritance in Animals and Plants
- Cell Division and Growth
- In body cells, chromosomes are found in pairs
- Body cells need to divide to produce new cells for growth or repair
- Mitosis produces identical new cells
- Has a 't' - two pairs of chromosomes - four chromosomes
- MIT - Making Identical Two
- Animal cells differentiate early in development but plant cells can differentiate at any time in their life
- Chromosomes contain genes (alleles) which pass on to each new cell
- When the cells are unspecialised they are called stem cells
- In asexual reproduction the cells of offspring are made by mitosis
- Mitosis Process
- Normal cell with two pairs of chromosomes (four chromosomes)
- A copy of each chromosome is made - 4 pairs, 8 chromosomes
- The cell divides to make it identical to the parent cell - two pairs, four chromosomes
- A copy of each chromosome is made - 4 pairs, 8 chromosomes
- Normal cell with two pairs of chromosomes (four chromosomes)
- Cell Division in Sexual Reproduction
- Gametes (sex cells) are produced by meiosis
- Gametes have one set of chromosomes (2 chromosomes)
- Sexual reproduction gives variation
- In humans, the gametes are sperm and ova
- How to remember
- Process of Meiosis
- Normal body cell - 2 pairs, 4 chromsomes
- Chromosomes copy - 4 pairs, 8 chromosomes
- Cell divides in two - 2 pairs, 4 chromosomes
- Divide again but separating the pairs so the pairs are different chromosomes - 1 pair, 2 chromosomes
- Cell divides in two - 2 pairs, 4 chromosomes
- Chromosomes copy - 4 pairs, 8 chromosomes
- Normal body cell - 2 pairs, 4 chromsomes
- Stem Cells
- Stem cells are not specialised
- They differentiate into many different types of cell when required
- They can be used to cure some types of disorders such as paralysis
- They can be found:
- in the human embryo
- in adult bone marrow
- Mendel and DNA
- Mendels factors are what we call genes
- Chromosomes are made o DNA - genes are short sections of DNA
- Each gene has a particular combination o amino acids to make a specific protein
- Inheritance in Action
- Humans have 23 pairs of chromosomes
- one pair are sex chromosomes
- females have two X chromosmes
- Males have one X and one Y
- one pair are sex chromosomes
- Some characteristics are controlled by a single gene
- Different forms of the same gene are called alleles
- Some are dominant and some are recesive
- Genetic Terms
- Phenotype - physical appearance (dimples, no dimples)
- genotype - genetic makeup - which allele do they inherit (Dd or dd)
- Homozygous - both alleles are the same (DD or dd)
- Heterzygous - both alleles are different (Dd)
- Humans have 23 pairs of chromosomes
- Inherited Conditions in Humans
- Some disorders are caused by genes and can be inherited
- If the allele is dominant the they only need to inherit one dominant allele to get the disorder
- Eg. polydactyly - extra fingers and toes
- Cystic fibrosis is caused by a recessive allele and causes the build up of mucus
- Genetic diagrams are used to predict the chances of offspring inheriting disorders
- Stem Cells and Embryos - Science and Ethics
- Embryonic stem cells can be used in medical research and treatments
- Embryos can be screened for genetic disorders
- There are economic, social and ethical issues with using embryonic stem cells
- Ethical - Could be babies, destroyed afterwards, baby can't give permission
- Economic - Embryonic research is expensive
- If parents decide to terminate the pregnancy it could be classed as murder
- Cell Division and Growth
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