Inheritance Flashcards
When are the times when mitosis occurs?
- When an organism is growing
- When an organism is damaged the cells need to produce new cells
What are the stages of meiosis?
- Original cells chromosomes are copied forming 92 chromosomes or 46 pairs.
- The cells divides into 2
- They divide another time
- Therefore the original has divided into 4 gametes.
Where are gametes found?
Gametes are found in the reproductive organs.
How are the chromosomes in the gametes?
The chromosomes are single and there are 23.
What are the gametes’ differences from each other?
The gametes are all genetically different from each other
What is the name of two gametes joining together?
Fertilisation
What happens after fertilisation in the cell in terms of chromosomes?
The two gametes join and the 23 single chromosome join together forming 23 pairs of chromosomes
Describe the link between the meiosis and fertilisation in terms of chromosomes
Whilst meiosis half’s the number of chromosomes in a cell, fertilisation the number of chromosomes is restored.
Describe the link between the meiosis and fertilisation in terms of chromosomes
Whilst meiosis half’s the number of chromosomes in a cell, fertilisation the number of chromosomes is restored.
Describe what happens in fertilisation in terms of meiosis and mitosis.
A Malé and a female gamete (eggs and sperms) join together to form a fertilised egg. Mitosis occurs and the cell copies and forms a clump of identical cells called an embryo. As the embryo develops ,through mitosis, the cells differentiate.
What are advantages of sexual reproduction
Variation in offspring
If the environment changes variation gives survival advantages by natural selection
Natural selection can be speeded up by humans in selective breeding to increase food production e.g cows
What are the advantages of asexual reproduction
Only one parents needed
Faster than sexual
More time and energy efficient coz no need for a mate
Many identical offspring when the conditions are preferable
Which organisms produce both sexually and asexually?
- Malaria parasites (asex in human host and sex in mosquito)
- Many fungi (asexually in spores but sex to give variation)
- Strawberry and Daffodil plants (sex for seeds and asex in runners for strawberry and asex as bulb division in daff)
Where is dna found?
In chromosomes in the nucleus in the cell.
What is dna?
A polymer made of molecules called nucleotides in two strands which make a double helix.
What are the different nucleotides?
A - T
C - G
What are the two bits in a nucleotide that never change?
Phosphate group and sugar molecule.
What is the one part of a nucleotide that does change from molecule to molecule.
The base (ATCG)
What form do nucleotides take?
Polymer as they line up with maybe even hundreds of them
What are the nucleotides pairings and why?
A - T
G - C
Because the two strands in the double helix of dna are complimentary.
What is a gene
Each gene codes for a particular sequence of amino acids to make a specific protein.
What is the genome?
The entire genetic material of an organism.
What is a stem cell
Cells that have not undergone differentiation.
What is an undifferentiated cell
A cell which is not yet specialised
What are the cells in early stages of developing of an embryo
Stem cells
What is an embryonic stem cell
A stem cell found in the embryo which can differentiate into any kind of cell
What is an adult stem cell
A stem cell that remains after embryonic stage and it can only differentiate into certain types of related cells
Where are adult stem cells located
Brain eyes blood heart liver bone marrow skin and muscle
What can bone marrow stem cells differentiate into
Blood cells and cells in the immune system
What are the advantages and risks of medical treatment with stem cells
Can help with diabetes and paralysis
Can transfer viral infections and ethical concerns
Problems with embryo screening
Expensive
Large number of embryos created but only small number is implanted so healthy ones are destroyed which can be unethical
In future can use embryo screening to produce offspring with better feature which is also unethical
Problems with embryo screening
Expensive
Large number of embryos created but only small number is implanted so healthy ones are destroyed which can be unethical
In future can use embryo screening to produce offspring with better feature which is also unethical
What is embryo screeening
Embryos are tested to see if they have the alleles for inherited disorders, embryos which don’t have the defective alleles are implanted
Gene therapy
In the future scientists may be able to correct faulty alleles which can treat inherited disorders however it is still experimental.
What is cystic fibrosis
A disorder of cell membranes, controlled by a single gene, C - normal membrane function dominant, c - defective cell membranes recessive
Polydactyl
Extra fingers and toes, caused by dominant alleles. Can’t be a carrier as when you have the dominant you will have the disorder.
