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Inheritence, Year 11 revision- Inheritance - Coggle Diagram
Inheritence
Key words
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Genotype- genetic makeup of an organism, consisting of all the alleles present
Phenotype- observable features of an organism as a result of the expression of particular alleles of the gene
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Syllabus information
Chromosome- thread like DNA, carrying genetic information in the form of genes.
Gene- length of DNA that codes for a protein.
Allele- version of a gene.
Inheritance- transmission of genetic information from generation to generation
Inheritance of sex in humans with reference to XX and XY chromosomes.
Sequence of bases in a gene is the genetic code for putting together amino acids in the correct order to make specific protein.
DNA controls cell function by controlling the production of proteins, antibodies and receptors for neurotransmitters
Protein in made:
- the gene coding for the protein remains in the nucleus
- mRNA molecules carry a copy of the gene to the cytoplasm
- the mRNA passes thorugh ribosomes
- the ribosome assembles amino acids into protein molecules
- specific order of amino acids is determined by the sequence of bases in the mRNA
Body cells in an organism contain the same genes, but many genes in a particular cell are not expressed because the cell only makes the specific proteins it needs
Haploid nucleus is a nucleus containing a single set of unpaired chromosomes e.g. in gametes
Diploid nucleus is a nucleus containing two sets of chromosomes e.g. in body cells
Diploid cell, there is a pair of each type of chromosome and in a human diploid cell there are 23 pairs
Monohybrid inheritance
Genotype- genetic make-up of an organism in terms of the alleles present
Phenotype- observable features of an organism
Homozygous- having two identical alleles of a particular gene
Two identical homozygous individuals that breed together will be pure-breeding
Heterozygous- having two different alleles of a particular gene
heterozygous individual will not be pure-breeding
Dominant- allele that is only expressed if it is present
Recessive- allele that is only expressed when there is no dominant allele of the gene present
Sex linked characteristics- characteristic in which the gene responsible is located on the sex chromosome and that this makes it more common in one sex than in the other e.g. colour blindness is sex linkage
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Co-dominance
Some alleles are co-dominant, meaning that neither is recessive, and they are both displayed in the phenotype. E.g. blood groups. Three possible alleles for blood groups are A, B and O. The A and B alleles are co-dominant, leads to the AB blood group. O is recessive, this is only displayed in the phenotype if both parents have O blood groups.
Sex-linked characteristics- Some genes are located on the sex chromosomes. Characteristic which comes from one of these genes is referred to as sex-linked characteristics. result of this is that some traits are more common to one gender. e.g. gene located on the Y chromosomes can only be present in males as females do not have that chromosome.
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