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30 Cards in this Set
- Front
- Back
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Name and explain the two types of variation. |
Discontinuous- All or nothing characteristics, it is either there is or there isn't Continuous- Where a characteristic takes a range of measured values e.g. hair length |
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What is a triplet code? |
Triplet code 3 bases (3 letter word e.g. ATC) will provide a code for the formation of an amino acid. Amino acids are the building blocks of proteins for an organisms body. |
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What are the 3 parts of nucleotides? |
Base, sugar and Phosphate |
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Name the 3 stages of D.N.A Replication? |
1. Enzyme unzips the D.N.A strand into two halves with create a fork. 2. New nucleotide unit will join onto each half 3. 2 identical D.N.A strands are produced each containing half of the original strand. |
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What is semi-conservative replication? |
DNA replication by unzipping a DNA molecule followed by the pairing of new nucleotides by enzymes to produce two new DNA strands with one original and one newly synthesised strand of DNA. |
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What is sexual reproduction? |
Sexual reproduction requires two parents a male and a female to produce a new individual. |
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What is Asexual reproduction? |
Asexual reproduction requires one parent to split into two to form a new genetically identical organism. These organisms are neither male or female. |
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What is a diploid cell? |
A diploid or 2n cell is cell that has a full set of chromosomes. |
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What is a Haploid cell? |
Haploid cell is a cell that has half the chromosomes. |
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What is the purpose mitosis ? |
The process of cell division used for growth, repair and asexual reproduction. |
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What is meiosis? And what is its purpose |
Meiosis is the process of cell division used for sexual reproduction as it creates sex cells or gametes. The purpose of meiosis is to increase genetic variation. |
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How is variation created in Meiosis? |
Crossing over- Sections of the chromatids exchange segments which creates a new combination of alleles. Independent assortment- When the 4 gametes at the end of meiosis receive random chromosomes. Each set of chromosomes are distributed independently of others. |
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How is variation created in sexual reproduction? |
Crossing over, Independent assortment Random recombination- After the creation of gametes the sperm fertilises the egg. And the combination of gametes is random which means it is random which chromosomes combine to make a full set for the offspring. |
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What is Pure Breeding? |
A homozygous organism can be referred to as pure breeding. As both alleles are the same and only code for one variation of a characteristic. |
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How does inheritance of the 23 chromosome work? |
The gender of an organism is determined by the male gamete (x or y) as the female always has X. And for each fertilisation the is always a 50% chance both ways for either a boy or a girl. |
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What is natural selection? |
Genetic diversity due to meiosis = disease may not affect all individuals because of different combination of genes= Some individuals are born resistant to diesease while others are not= those who are naturally immune breed= pass on the immune phenotype= evolution SURVIVAL OF THE FITTEST |
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How do mutations occur? |
Permanent change in D.N.A sequence or number of chromosomes. Mutations can only occur in sex cells. |
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What happens in base sequence mutations? |
Base sequence is changed= different amino acids produced= different proteins= different characteristic. |
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How would you describe the D.N.A structure |
1. Sugar phosphate backbone 2. Bases a-t and c-g 3. Base pairs 4. Double helix 5. Nucleotides 6. Triplet codes |
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How does D.N.D code for a characteristic? |
1. Base pairs 2. 20 triplets of base code 3. 20 Amino acids then create 1 protein 4. Proteins build an individuals body 5. Form characteristics or phenotypes |
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Who is a carrier? |
Someone who has inherited a genetic trait or mutation, but do not display that trait, and can pass it on to their offspring. |
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Define complementary base pairing? |
Used to describe how bases bond a-t and c-g |
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What are hydrogen bonds? |
Attractive forces that hold two strands of D.N.A together. |
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Define Incomplete dominance |
A situation where neither of the two genes (alleles) mask each other |
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What is a Karyotype? |
A diagram or photograph of the chromosomes of a cell arranged in a orderly fashion. |
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What is ribose? |
A sugar group that alternates with the phosphate group in the backbone of D.N.A |
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What is a genotype? |
This is what genes you carry |
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Define Phenotype. |
The expression of the genotype, what you look like. |
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Define selective breeding. |
A process that is used to breed for specific required traits. |
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What is biodiversity? |
The variation of a species in a eco-system |
