Genetics and reproduction Flashcards
The aim of reproduction is…
To perpetuate the hereditary characteristics of a species, and to mix up DNA to ensure better chances of a species’ survival
DNA structure
Double helix containing nitrogenous bases, ribose sugars, and phosphate groups
Nitrogenous bases
Adenine and thymidine
Guanine and cytosine
Chromosomes are…
Two long strands of DNA, one maternal and one maternal, each called a chromatid
DNA to protein
- DNA unravels and is transcribed to mRNA
- mRNA carries protein code to ribosome
- tRNA decodes mRNA message by presenting an anti-codon and linking corresponding amino acids together
A gene is…
A segment of DNA that codes for a specific protein and is responsible for a specific phenotype/trait
Mendel’s Law of Segregation
Pairs of traits (alleles) separate during gamete formation and randomly re-unite on fertilisation
Mendel’s Law of Independent Assortment
Trait pairs separate independently during gamete formation, i.e. traits are transmitted to offspring independently of one another
Genotype vs phenotype
Genotype is genetic make-up
Phenotype is an observable characteristic
Inherited vs familial
Inherited is genetic information given from the parents
Familial is a phenotype seen in two or more family members which may or may not have a genetic basis
Alleles are…
Genes that contain different descriptive data about the same trait
Homozygous vs heterozygous
Homozygous means that two genes received from the parents are the same, heterozygous means they are different
Types of allele
Dominant, recessive, and incompletely dominant (influenced by other genes)
Overdominance is…
When a heterozygous allele pair have enhanced characteristics compared to a homozygous pair, e.g. malarial resistance in heterozygous sickle cell carriers
Co-dominance is…
When two alleles are equally dominant, e.g. in blood groups
Genetic disorders (3)
- Single gene/Mendelian - common
- Polygenetic/multi-factorial complex diseases, e.g. diabetes type II
- Chomosomal conditions, e.g. Down’s syndrome
Epistasis
The ability of one gene to affect the function of another, e.g. diabetes mellitus is an epistatic illness involving up to 7 genes
Pleotropism is…
When a gene has more than one effect
Polymorphisms are…
Commonly occuring variants of an allele in a specific population (e.g. an ethnic group)
Mitosis is…
Non-reproductive cell division, resulting in two identical daughter cells
Diploid cells with 23 pairs of chromosomes identical to parent cell
Process of mitosis
Interphase - DNA doubles
Prophase - nuclear membrane breaks down, centriole spindle formation begins
Prometaphase - chromosomes attach to spindles
Metaphase - chromosomes align at the equator of the cell
Anaphase - duplicate chromosomes are separated by spindles shortening
Telophase - chromotids reach poles and cells pnch into two at the equator
Meiosis is…
Reproductive cell division, resulting in 4 daughter cells (haploid) with 23 chromosomes each
Process of meiosis
Prophase I - nuclear membrane breaks down, ‘crossover’ where DNA is exchanged between chromatids
Metaphase I - chromosomes align at the equator
Anaphase I - chromosomes are pulled to each pole
Telophase I - cell pinches to create 2 sister cells
Meiosis II - mitotic division, but DNA does not replicate
