Inheritance mindmap
- Created by: ava.scott
- Created on: 09-04-15 19:07
View mindmap
- Inheritance
- terms
- Genetics
- the study of the mechanisms by which organisms inherit characteristics from their parents,
- Genotype
- the genetic makeup of an individual. includes all the allele combinations.
- Allele
- diifferent versions of the same gene.
- Phenotype
- the physical characteristics of a organism.
- Genetics
- Genes
- They can separate and combine
- they can mutate
- they code for a specific polypeptide
- Monohybrid inheritance
- Involves
- the inheritance of a single characteristic by a single gene
- Punnet square
- make sure you label x and y labels with gametes from each parents
- Mendels first law
- characteristics come in pairs called factors (alleles) but only one allele can be present in a gamete.
- Involves
- Dihybrid inheritance
- Involves
- the inheritance of two separate characteristics by two genes.
- To find a ratio, you divide the amount of each phenotype by the smallest one.
- mendels second law
- either one of a allelic pair can combine freely with one of another pair.
- Involves
- CHI2
- expected ratio of a dihybrid is always 9:3:3:1
- we use this statistic test to see if any variations in data ae down to chance or not.
- Must be below 5% to be insignificant.
- EQUATION
- (O-E)^2/E
- CO-DOMINANCE
- When a individual is heterozygous dominant.
- both alleles are expressed equally in the phenotype.
- Parents would have to be homozygous dominant.
- Sex determination and linkage
- X and Y chromosomes. **= girl XY= boy.
- Alleles of the X chromosome ae described as sex linked.
- because the Y chromosome carries few alleles
- Haemophilia
- A recessive allele on the X chromosome, which stops people from clotting.
- Mainly boys as they only need to inherit one copy of the recessive allele.
- Linkage
- When two different genes are on the same chromosome and they are generally inherited together.
- Separated by crossing over.
- which only occurs in 10% meiotic divisions.
- Doesnt follow typical mendelian pattern.
- MUTATIONS
- diiferent types
- gene
- Changes in the base pair within the gene producing a different allele.
- modifies the polypeptide by the primary sequence.
- sickle cell anaemia
- One mutation results in a different amini acid (glutamic acid instead of valine in the 6th position of the Beta globulin chain) in haemoglobin.
- This reuslts in it beocming a sickle cell shape, and less able to carry oxygen, resulting in anaemia and possible death.
- Changes in the base pair within the gene producing a different allele.
- chromosome
- changes in structure or whole number of chromosomes.
- usually occur in meosis during metaphase 1.
- change structure
- crossing over matches up genes in the wrong way
- numbers
- non-disjunction
- chromsomes dont separate properly, so daughter cells receive unequal numbers.
- e.g. downs syndrome
- non-disjunction
- sets
- increasing number of complete sets/ polyploidy
- often found in plants and associated with beneficial characteristics.
- usually results in infertility.
- gene
- mutation rate
- spontaneous events so small rate
- organisms with shorter life cycles have a higher rate of mutation.
- increased by mutagens
- ionising radiation e.g. UV, gamma
- polycyclic hydrocarbons in cigarette smoke
- occur mainly in somatic cells.
- only those which occur in germinal cells can be inherited.
- Carcinogens
- mutagens that increase chance of cancer;
- usually effects proto-oncogenes or tumour-suppressor genes
- Importance
- somatic mutations can lead to cancer
- mutations cause sudden and distinct differences basis of discontinuous variation.
- most mutations are recessive so must await many generations before meeting another of its kind.
- diiferent types
- terms
Similar Biology resources:
Teacher recommended
Comments
No comments have yet been made