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B6 - Final Mocks - Coggle Diagram
B6 - Final Mocks
Alleles
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The genotype of a person tells us the alleles present. If a person has 2 copies of the same allele, we say that they are homozygous.
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If a person has 2 different alleles, they are known as heterozygous. The phenotype shown here is dependent on which allele is recessive and which is dominant.
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DNA and the Genome
Chromosomes contain the molecule DNA, a genetic material that determines out inherited features.
A gene is a small section of DNA on a chromosome; each gene encodes for a specific sequence of amino acids to form a specific protein.
The genome is the entire genetic material of an organism; the human genome has been studied completely. This is beneficial as this allows us to search for genes that are linked to specific diseases such as genes that increase risk of cancer. It also helps us understand and treat inherited disorders such as cystic fibrosis. We can also use the human genome to track human migration patterns from the past and discovery ancestry.
Protein Synthesis
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Stage 1:
- Known as transcription.
- Takes place in the nucleus.
- Base sequence of gene is copied into a single-stranded template molecule (mRNA).
- The mRNA passes out the nucleus and into the cytoplasm.
Stage 2:
- Known as translation.
- mRNA molecule attaches to a ribosome.
- Amino acids are brought to the ribosome via tRNA molecules.
- The ribosome reads the triplets of bases on the mRNA and assembles the correct amino acids in the correct order.
Polydactyly
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In embryo screening, embryos are tested to see if they possess certain alleles. One problem from this is expense and only a small number of embryos are actually implanted so ethical concerns arise.
In the future, we may be able to produce embryos with more "desirable" characteristics, many may see this as unethical.
Mutations
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Most mutations do not have an effect on the function of a protein as different base triplets can sometimes encode the same amino acids.
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Meiosis
When a cell divides to form gametes, copies of the genetic information are made and the cell divides twice to form 4 gametes; each gamete has 23 chromosomes. All of these gametes are genetically different.
DNA Structure
DNA is a polymer of nucleotides that contain 3 parts: a phosphate group, a sugar molecule and a base. There are 4 different bases (ATCG). These molecule are complementary.
Cystic Fiborisis
Cystic fibrosis is a disorder of cell membranes, it is controlled by a single gene that has two alleles (C and c) where C is normal cell membrane function. A defective allele has to be inherited from both parents.