B5.1 - Inheritance Flashcards
Allele
Different version of the same gene
Gene
Unit of inheritance
A sequence of bases that code for a specific protein
Phenotype
The expression of the genotype/appearence
What factors can affect the phenotype
Environmental changes
Genotype
Random muration
Variation
Differences within a species
Often a result of random mutation
Genetic variation
Caused by genes inherited from parents
What can be affected by genetic variation
Eye colour
Hair colour
Blood group
Presence of a genetic disorder
Most features are caused by multiple genes
True
Discontinuous variation
Eye colour
Something which is a set value
Continuous variation
Can be anything within an infinite range
E.f. Heihgt
Characteristics of asexual reproduction
Faster
Needs only one parent
More offspring produce
Genetically identical offspring/clones - this reduces variation and leaves the species more vulnerable to pathogens
Characteristics of sexual reproduction
Two parents, male and female
Slower
Less offspring
NOT genetically identical - meaning more variation - which is good
Happens mostly in animals, in some plants
Diploid
Full number of chromosomes
These are the normal body cells
Haploid
Only half the number
In gametes
Name of cell after fertilisation
Zygote/embryo - which then replicates with mitosis to make new organisms
Difference between meiosis and mitosis
Mitosis - 2 genetically identical daughter cells are made, makes diploid cells
Meiosis - 4 NOT identical daughter cells produced, makes haploid cells, makes gametes
Dominant allele
A version of a gene which only requires one or more of it to present in a genotype, for it to be expressed
Recessive allele
A version of a gene which has to have two of it present to be expressed
Homozygous
Two same allels
Heterozygous
Two differnt alleles
How can u predict a genetic cross
Use a pinnet swuare
How to determine male or female from the 23rd pair of chromosomes
XY is male - hence a sperm cell carries either an X or a Y
XX is female, hence egg cells can only carry X
Mutation
Random change within the sequence of DNA bases
What can mutations lead to
Cancer - divine uncontrollably
Production of abnormal proteins
Cause different shaped proteins to be made
Some mutations do. Nothing
Some are beneficial - e.g. antibiotic resistance in bacteria