2b.3 - DNA, Meiosis and Mitosis Flashcards
What does DNA contain?
Instructions to put an organism together and make it work
Where is DNA found?
In the nucleus of animal and plant cells in long molecules called chromosomes
What is a gene?
A section of DNA
What do genes contain?
Instructions to make a specific protein
How do cells make proteins?
Stringing amino acids together in a particular order
How many amino acids are used to make thousands of different proteins?
20
How many different proteins can 20 amino acids make?
Thousands
What do genes do?
It tells cells in what order to put the amino acids and what proteins the cells produce
What are the exceptions to ‘everyone’s DNA is unique’? (2)
- Clones
- Identical twins
What is DNA fingerprinting?
It is a way of cutting up a person’s DNA into small sections and then separating them
What is DNA fingerprinting used for? (2)
- Forensic science
- Paternity testing
What are the advantages to there being a national genetic database?
Easier to solve crimes
What are the disadvantages to there being a national genetic database? (3)
- Invasion of privacy
- Sceptical as to what else it could be used for
- False positives or misinterpretations
What does mitosis make?
New cells for growth or repair
How does mitosis reproduce itself?
By splitting to form two identical offspring
Describe the process of mitosis (5)
- Cell gets a signal to divide
- Duplicates itself
- Chromosomes line up along the centre
- Cell fibres pull them apart
- Membranes form and the cytoplasm divides
What type of reproduction uses mitosis?
Asexual
What are gametes?
Sex cells with half the usual number of chromosomes
How many divisions does mitosis involve?
One
How many divisions does meiosis involve?
Two
Where is the only place meiosis happens?
The reproductive organs
What type of cells does meiosis produce?
Cells which have half the normal number of chromosomes
Describe the process of meiosis (5)
- DNA duplicates
- Chromosome pair line up along the middle
- Pulled apart by cell fibres
- Chromosomes line up again and pulled again
- Four gametes with a single set of chromosomes
