Genetics Flashcards
What is a gene?
- Biological set of instructions which tells a cell how to develop, hence determines the characteristics of an organism
- And is located on chromosomes
What are chromosomes?
- Contains protein and DNA
- Like pieces of wound up string
- Exist in pairs, members in each pair is the same shape and size
Is an organism more complex if they have more chromosomes?
-No, characteristics are determined by the genes inside chromosomes, not the amount of chromosomes there are
How many chromosomes are inherited from the father and the mother?
23 from the father and 23 from the mother.
How many homologous pairs do we have?
22
What are chromosomes arranged according to?
The chromosomes are numbered and arranged to their size, 1 being the largest
What type of cell are most cells in our body?
Diploid cells, as they contain 2 of each type of chromosomes
What type of cells are sex cells?
Sperm or ova are haploid cells as they have only one chromosome of each type
What are sex chromosomes in mammals called?
X and Y chromosomes
What defines the gender of the offspring?
Whether the chromosome is an x or Y chromosome
What does a sperm cell contain?
Either an X or Y chromosome with 22 other chromsosomes
What does an ova contain?
Contain an X chromosome and 22 other chromosomes
What is the difference between Y and X chromosomes?
Y chromosomes is smaller than X and contains fewer genes
Why is cell division necessary?
necessary for growth, repair and reproduction
What happens in mitosis and where does it occur?
- Type of cell division
- Occurs in every cell except sex cells
- Produces two diploid cell for every one parent cell
- Daughter cells are identical to parent cells
Where does meiosis occur?
Only in sex cells, hence occurs in testes to produce sperm and ovaries to produce eggs.
What happens in meiosis?
- Four daughter cells are produced
- Daughter cells are haploid and non- identical
- Daughter cell contain one of each type of chromosome
What is a gamete?
Daughter cell produced by meiosis and one gamete contain only of each type of chromosome.
What is a zygote?
Produced by when a sperm fertilises an egg, has a total of 46 chromosomes
What does DNA stand for?
deoxyribonucleic acid
What is the composition of DNA?
- Composed of 2 bases and strands
- Strands are made out of sugar and phosphate
- Double stranded with each base on one strand being weakly bonded to its base pair on the opposite strand
- Bonding make the two strands to bridge together to for a double helix
What are characteristics of an organism determined by?
The genes included within the DNA strand
What are bases and what are they made up of?
- 4 bases include: adenine, thymine, cytosine, guanine
- And are made up of nitrogen
Why does only A bond with T, and C with G?
due to their chemical structure
Why are organisms different?
As the proteins which make up their cells are different
What tells the body what type of protein to make?
A gene consists of a section of DNA
What is the difference between one gene and another?
Order of the bases
Why are proteins important?
Proteins are responsible for cell structure and function
How is a protein molecule made?
Any three bases, code a triple code aka codon, with one codon coding for one amino acid, to make up a part of protein molecule
How many codons are possible?
64
Why does amino acids have various codons to produce it?
as there are only 20 amino acis
What is the START and STOP codons responsible for?
Indicate where the amino acid should start as well as the end of the chain.
What is replication? What happens in replication for it to occur?
- When the DNA in the chromosome copies itself
1) Weak bonds between the base pairs break
2) DNA untwists and unzips
3) Spare bases in the chromosome match up with it complementary base on the unzipped strand
4) A new strand begins to build on each of the old strand
5) One of each section is copied, the old and new strand are zipped together to form an identical copy of the original DNA
