4.3 Inheritance Flashcards
What is the definition of allele?
Variations of the same gene
What is the definition of gene?
A section of DNA that codes for a polypeptide
What is the definition of dominant?
Will be expressed in even when heterozygous
What is the definition of recessive?
Only expressed when homozygous
What is the definition of phenotype?
Physical expression of a gene
What is the definition of genotype?
Combination of alleles
What is the definition of homozygous?
Alleles for a characteristic are the same
What is the definition of heterozygous?
Alleles for a characteristic that are different
What is Mendals first law?
Law of segregation
All characteristics are determined by alleles tat occur in pairs
only one form each pair can be present in a single gene
What is Mendals second law?
Law of independent assortment
Each pair of alleles may combine randomly with either of another pair
What is Dihybrid inheritance?
The simultaneous inheritance of two alleles determined by two genes on different chromosomes
What ratio did Mendal conclude for F2?
9:3:3:1
What is a test cross?
Crossing dominant phenotypes wit homozygous recessive
When is H0 rejected?
If the result exceeds the critical value and is therefore significant
What are the exceptions to mendals law?
Co-dominant alleles
Sex linked genes
Non independent assortment
What is sex linkage?
Alleles linked to the X or Y chromosome
What are some examples of sex linked diseases?
Red/green colour blindness
Haemophilia
What is codominance?
When alleles are expressed equally in the phenotype (e.g. Red, pink and white)
What us a mutation?
a change in the sequence of base pairs in a DNA molecule that may result in an altered polypeptide
What is an ancogene?
A mutation allowing cells to divide uncontrollably
What is a mutagen?
A factor causing a mutation
What is a Insertion/deletion mutations? And what is it impact?
When 1 or more nucleotide pairs are inserted or deleted from the sequence
Causes a frameshift in the sequence of nucleotides
What is point mutation/substitution?
where one base pair is replaced by another
What is an Oncogene?
A gene that can develop into a tumor
What is the impact of cancer to the body?
Inhibited bodily functions
What is the impact of cancer to the body?
Inhibited bodily functions
How is sickle cell anaemia caused?
A gene mutation to the gene producing haemoglobin
Glutamic acid is replaced with valine
Polypeptide chain is altered producing Haemoglobin S
How is sickle cell anaemia inherited?
Mutated gene is codominant
Homozygous = sufferer
Heterozygous= 30-40% chance of suffering
What are the symptoms of sickle cell?
RBC carrying capacity decreased
joint pain
organ damage
distorted blood vessels
What is a silent mutation?
Multiple codons for 1 amino acid so sequence changes but not amino acid produced
What is epigenetics?
Control of gene expression with factors outside of sequencing
What is methylation of cytosine?
Histone modification after translation nucleosomes pack less tightly making histones more accessible and therefore more transcription occurs
What are the consequences of epigenetic changes?
genomic imprinting
x inactivation
What is genomic imprinting?
Inactivation of a gene/genes passed down generations leading to permeant switching off and genetic conditions
What is X inactivation?
Whole chromosome inactivation
cells of female mamals will use only one X chromone and the other dense chromatin Barr body
What does epigenetics control?
How likely transcriptions are
Post transcription alterations
What factors impact epigenetics?
Lifestyle
mental health
Physical health
Weather
chemical or biological exposure
What is an epigenome?
The accumulation of environmental signals received in life
What is Hyper-methylation?
Tumour suppressant inhibited
so no control of tumour growth
What is hypo-methylation?
lack of methylation
What is hypo-methylation?
lack of methylation
What is hypo-methylation?
lack of methylation
