Genes Flashcards
What chemical is the basis of inheritance
DNA
Whereas DNA found
Nucleus in chromosomes
What is a small section of DNA that determines a particular feature
A gene
How do genes determine features
Instruct cells to produce particular proteins which leads to development of the feature
What does mitosis form
A genetically identical cell with the same type and amount of DNA
What is a molecule of DNA made of
Two strands of nucleotides so it is polynucleotide
What does each nucleotide contain
Nitrogenous base , phosphate group and sugar molecule
What are the nitrogenous base pairs and how do they work
Complimentary base pairs always bind with each other
Adenine and thymine
Customise and guanine
Which part of DNA codes for manufacture proteins
Sense strand , the other strand is the anti sense strand
What views for one amino acid
A sequence of three nucleotides . The base sequence codes for the amino acid . 3 bases = 1 amino acid. DNA code is a triple code . The sequence of based that codes for all the amino acids in a protein is a gene
What is a mutation
A change in the DNA of a cell An happen in individual genes or whole chromosomes
How does mutation happen
When DNA is replicating mistakes are made and the wrong nucleotide is used . The result is a gene mutation that can alter the sequence of bases in a gene that can lead to the gene coding for the wrong protein
What is duplication
Form of mutation . The nucleotide is inserted twice instead of once and the entire base sequence is altered - each triplet after the point where the mutation has altered . Whole gene is different and codes for an enitirely different protein
What is deletion
Mutation. Nucleotide is missed out. Entire base sequence altered each triplet after mutation changed whole gene different codes for different protein
What is substitution
Different nucleotide used. Triplet of bases where mutation occurs is changed and may code for different amino acid . If it does the structure of protein moclecuke will be different. This may be enough to produce an alteration in the functioning of the protein or lack of function . Triplet may not code for a different amino acid as they normally have more than one code
Inversions
Sequence of bases in the triplet is reversed. Only one triplet affected may or may not result in a different amino acid and altered protein structure
What happens to harmful mutations
Mutations in body cells affect that particular cell. If they are harmful the cell will die and then mutation will b lost
What happens to non harmful mutations
If the mutation does not affect the functioning of the cell in a major way the cell may not die if the cell then divides the mutation will be passed on
How can mutations be passed on to next generations
Organism dies , mutations die with it unless mutations are in sex cells or cells that divide to form sex cell then mutation will be passed on to next genration and genetic diseases begin
When are mutations advantageous
As a result of random mutations bacteria can become resistant to anti biotic . They become advantageous over non resistant bacteria and They will survive antibiotic treatment and reproduce and the mutation will be passed on. Proportion of resistant bacteria will increase as they survive
What are mutagens
Agents that increase mutations
- ionising radiation ( X-ray , uv light , gamma rays
- chemicals such as mustard gas , nitrous oxide , tar ,
What is DNA cooked around in chromosomes
Histones . Each chromosome contains one double stranded DNA molecule that is folded and coiled around proteins called histones
How many chromosomes on a diploid
46
Matching chromosomes
Homologous pairs . Carry genes for the same feature in the same sequence