Reproduction Flashcards
All 9 cards in this deck
What does meiosis (meiotic cell division) produce?
Four genetically different haploid daughter cells — the gametes (sex cells).
Why must gametes be haploid?
So that when two gametes fuse at fertilisation the zygote is diploid, restoring the normal chromosome number (46 in humans).
Describe the structure of a DNA molecule.
A polymer of two strands of nucleotides coiled into a double helix; each nucleotide is a sugar, a phosphate group and one of four bases, and the strands are linked by complementary base pairs joined by weak hydrogen bonds.
Which bases pair together in a DNA molecule?
A pairs with T, and C pairs with G (complementary base pairs, joined by weak hydrogen bonds).
What is meant by the genome, and what is a gene?
Genome = the entire DNA of an organism. Gene = a section of a DNA molecule that codes for a specific protein.
When extracting DNA from fruit, why are detergent and ice-cold alcohol used?
Detergent breaks down the cell membranes to release the DNA. DNA is insoluble in ice-cold alcohol, so it comes out of solution as white strands.
What is meant by a haploid cell?
A cell with half the number of chromosomes of a body cell.
e.g. a human gamete has 23 chromosomes (body cells have 46).When extracting DNA from fruit, why is salt added?
It makes the DNA clump together, so it is easier to separate out.
What is meant by a diploid cell?
A cell with two sets of chromosomes, so its chromosomes are in pairs.
e.g. a human body cell has 46 chromosomes (23 pairs).