Genes/natural selection and genetic modification Flashcards
What is formed when the two gametes fuse during fertilisation?
Zygote
What is the DNA of an organism?
It’s genome
Diploid?
2 sets of chromosomes= 46 chromosomes
Haploid(sex cells)
One set of chromosomes= 23 chromosomes
What does meiosis produce?
Haploid cells-gametes
What does mitosis produce?
Diploid cells
Meiosis summary?
The cell that makes gametes is a diploid cell. The chromosomes replicate and copies get stuck together. The then divide into two and two again. Each of the 4 final daughter cells have 1 chromosomes from each pair. They are haploid
What does nuclei contain?
Long molecules of DNA, each molecule tightly packed with proteins to form chromosomes
Shape/structure of DNA?
Double helix
Two strands bonded together my pairs of substances called bases.
4 bases in DNA?
Guanine+ Cytosine
Adenine+ thymine
Complimentary base pairs
How does each base attach to the strands?
Each base is attached to a sugar, which is attached to a phosphate group (which forms the backbone of the DNA strand)
How many hydrogen bonds between C and G?
3
How many hydrogen bonds between A and T?
2
What are alleles?
Different forms of genes
Homozygous?
If both alleles for the gene are the same
Heterozygous?
If the alleles for the same gene are different
How many recessive genes needed to bring forth that characteristic?
2- both need to be recessive
How many dominant alleles needed to carry out that characteristic?
1
Genotype?
Alleles for an organism
Phenotype?
The appearance of these characteristic
Female and male sex chromosome?
Women carry X always, male carry either X or Y
Mutation?
A change in a gene that creates a new allele
Acquired characteristics?
Genes changed due to the environment during lifetime, eg. Loss of a limb