4. Genetics Flashcards
What is meant by genome
All the genetic material of an organism
What are chromosomes
Genetic structures that function in pairs
they are found in the nucleus of a cell
They are made up of genes and DNA
What is a gene
A section of a chromosome that control a particular characteristic eg hair colour
What is an allele
Different forms of the same gene e.g. gene for hair colour may have a brown hair allele, blond hair allele, black hair allele
What is DNA
made up of nucleotides that are joined together by the sugar - phosphate back bone
What are the 4 types of bases found on a nucleotide
A, T, G, C
What base pairs occur between bases of nucleotides
A base pairs with T
G base pairs with C
How does DNA work
DNA codes for the order of the amino acids in a protein
The base code is always in groups of 3 - known as the triplet code
If a gene has 54 bases along its coding strand for a protein. How many amino acids make up the protein
1 amino acid -= 3 bases
54/3 = 18 amino acids
What is the shape of DNA called
Double Helix
What are the most common proteins DNA produce
Enzymes - which control the development of a cell
What happens in mitosis
Mitosis is cell division to produce replacement cells, repair cells or for growth
Before division the chromosomes in nucleus make a complete copy of themselves
They line up at the middle of cell and then divide into 2 daughter cell
Each daughter cell has exactly the same number of chromosomes as the original (diploid cells)
What is meiosis
Cell division that happens to produce gametes - sperm and egg cells
Before division chromosomes duplicate (double the number)
Involves 2 cell divisions
Produce 4 daughter cells that have half the genetic information as the original cell (haploid cells)
What is independent assortment in meiosis
How the chromosomes separate the pairs of chromosomes is random so can lead to variation in the combination of each chromosome in each gamete
Why is meiosis important
When the sperm and egg join at fertilisation it ensures that the diploid number of chromosomes (23 pairs) is restored