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
Evolution order?
Ardipicethecus ramidus, Australopithecus afarensis, homo habilis, homo erectus, homosapiens
Stages of Darwin’s theory?
Genetic variation
Environmental changes causes competition with organisms
Variation of some individuals make them more likely to survive in the conditions
These are passed down to their offspring
Natural selection repeatedly occurs creating new better adapted species
5 kingdoms?
Animals, plants, fungi, prokaryotes, protists
Characteristics of animals?
Multicellular (cells made into tissues and organs, have nuclei and no cell wall
Characteristics of plants?
Multicellular, cell walls, chloroplasts for photosynthesis
Fungi characteristics?
Multicellular accept yeast and contain nuclei, live in or on dead matter on which they feed on
Protists characteristics?
Mostly unicellular, have nuclei
Prokaryotes characteristics?
Unicellular, no nuclei
Selective breeding?
Breeding for specific characteristics
Genetic engineering?
Changing an organisms genome by inserting genes from another
Risks with selective breeding?
If one organism is affected by something, they all are. Useful alleles may completely disappear
Risks with genetic modification?
Those plants tend to be more expensive
Genetic engineering of bacteria?
Restriction enzymes leave a couple bases unpaired- ‘sticky ends’
Use same enzyme to cut into plasmid again leaving sticky ends
Sections of DNA containing the insulin gene mix with the cut plasmid , enzyme ligase is used to help the bases now pair up
Plasmids are then inserted back to the bacteria and bacteria is grown
Strengths and weaknesses of sexual reproduction?
S- genetically diverse, of one is susceptible, they aren’t all
W- mate required
Asexual reproduction strengths and weaknesses?
W-genetically identical so of one is susceptible, they all will be and die out
S- don’t need a mate
Differences between mitosis and meiosis?
Mitosis- produce 2 identical daughter cells, used for growth and repair, produce diploid cells
Meiosis- 4 different daughter cells, used for sexual reproduction, produce haploid gametes
How to extract DNA practical?
Mash up Add salt water Add detergent Leave 15 mins Filter Add iced ethanol DNA flows to the top
Gene?
Stretch of DNA with codes for characteristics
Genome?
All genes in the body
Chromosome?
Bundled up DNA
Allele?
Different versions of a gene
Dominant?
Only one gene needed to express characteristic
Recessive?
Two identical genes to express characteristic
Homozygous?
Genes are the same
Heterozygous?
Genes are different
Genotype?
What genes you have
Phenotype?
Collection of characteristics you have
How many chromosomes in humans?
23 pairs- 46 in total
Female gene?
XX
Male gene?
XY
Human genome project aims and achievements?
Aimed to determine sequence of base pairs in a genome. They achieved faster sequencing for future and allowed faster advances in personalised medicine
Evidence for evolution?
Fossils- bones- shows change and relations between animals
Bacteria
How bacteria can come antibiotic resistant?
Divide rapidly, allows single mutations to spread quick, antiobiotic resistance can spread very quickly as the resistant live on
Recessive blood group?
O
Dominant blood groups?
A and B