Sexual reproduction
Involves the fertilisation of a male sex cell (sperm) and a female sex cell (egg cell)
Asexual reproduction
Produces clones of the organism, no fertilisation
Fertilisation
A male and female gamete fuse together to form a zygote
Haploid
1 set of 23 chromosomes (23)
Diploid
2 sets of 23 chromosomes (46)
Mitosis outcome
- 2 genetically identical daughter cells
- used for growth and repair
- Diploid cell
- One cell division
Meiosis outcome
- produces 4 genetically different daughter cells
- Haploid cell
- Two cell divisions
Advantages of Asexual reproduction
- produce lots of offspring quickly
- Only one parent is needed, don’t need to wait for a mate
Disadvantages of Asexual reproduction
- No genetic variation between offspring
- So, if environment changes it may be unfavourable for the whole population
Advantages of Sexual reproduction
- Creates genetic variation within a population
- If environment changes, some individuals in population will have the characteristics to survive
Disadvantages of Sexual reproduction
- Takes longer, fewer offspring is produced in their lifetime
- Two parents are needed for SR
Polymers are made up of…
Repeating units called nucleotides
Each nucleotide consists of…
A sugar, phosphate & one base
Which bases are complementary to each other?
A - T
C - G
DNA molecule has…
Two strands coiled together in the shape of a double helix
What are the complementary base pairs joined together by?
Weak hydrogen bonds
Extracting DNA from fruit: Step 1
- Mash strawberries
- Put them in a beaker of detergent and salt, mix it
What is the purpose of putting the strawberries in detergent?
Breaks down the cell membranes to release the DNA of the strawberries
What is the purpose of putting the strawberries in salt?
It will make the DNA stick together
Extracting DNA from fruit: Step 2
- Filter the mixture
- Get the big, insoluble bits of cell out
Extracting DNA from fruit: Step 3
- Add some ice cold alcohol to filtered mixture
Extracting DNA from fruit: Step 4
- DNA will start to come out of the solution as it’s not soluble in cold alcohol
- Appears as a white precipitate
