7.1 Genetic variation

Anisha Rai
Flashcards by Anisha Rai, updated more than 1 year ago
Anisha Rai
Created by Anisha Rai over 4 years ago
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GCSE Biology (7 Variation and inheritance) Flashcards on 7.1 Genetic variation, created by Anisha Rai on 04/25/2016.
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Why might an individuals have differences in characteristics of the same kind? Differences in: The genes they have inherited (genetic causes) The conditions in which they have developed (environmental causes) A combination of the above
What carries the information that results in plants and animals having similar characteristics to their parents? Genes
How are genes passed on? In the sex cells (gametes) from which offspring develop
Where are chromosomes found? In the nucleus of a cell
What do chromosomes carry? Genes that control the characteristics of the body
How are chromosomes found? In pairs
How many pairs of chromosomes are there in a cell? 23 pairs of chromosomes
How many paris of chromosomes in human body cells carry the genes that determine sex? One
Which are the sex chromosomes in females? XX
What are the sex chromosomes in males? XY
What do different genes control? The development of different characteristics of an organism
What are alleles? Different forms of the same gene
What is homozygous? If both chromosomes in a pair contain the same allele of a gene
What is heterozygous? If the chromosomes in a pari contain different alleles of a gene
What is a dominant allele? An allele that controls the development of a characteristic when it is present on only one of the chromosomes
What is a recessive allele? An allele that controls the development of a characteristic only if the dominant allele is not present
Which principles did Mendel use in mono hybrid inheritance in peas? He was trying to explain why some characteristics (such as white flower colour) disappear in one generation but reappear in the next Interpreted his results in terms of separate 'inherited factors', which we now call genes Mendel's work preceded the work by other scientists which linked Mendel's 'inherited factors' with chromosomes
What is phenotype? The physical appearance resulting from inherited information e.g. someone with blue eyes has the phenotype blue eyes
What is genotype? The genotype is the DNA sequence that determines the characteristic (phenotype)
What are the two forms of reproduction? Sexual reproduction Asexual reproduction
What is sexual reproduction? The joining (fusion) if male and female gametes The mixture of genetic information from two parents leads to variety in the offspring
What is asexual reproduction? No fusion of gametes and only one individual is needed as the parent There is no mixing of genetic information and so no genetic variation in the offspring These genetically identical individuals are known as clones
What are chromosomes made up of? DNA
What does DNA stand for? Deoxyribonucleic acid
What does DNA contain? The coded information that determines inherited characteristics
What is a gene? A small section of DNA
What does each gene code for? a particular combination of amino acids, to make a specific protein
What are the strands of DNA called? Double Helix
What do double helix's contain? Four different compounds, called bases
What does a sequence of three bases code for? A particular amino acid
What does the order of bases control? The order in which amino acids are assembled to produce a particular protein
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