Unit 3: Genetics

Meiosis II

Meiosis I

Chapter 13

Genes: Genetic code inherited from parents that determines an organism's traits.

Asexual reproduction: When an organism is the only parent and passes its genes to an offspring without the use of any gametes.

Sexual reproduction: When an offspring is given a unique mix of genes from two parents.

An example of a clone.

Clone: Offspring produce in asexual reproduction.

Chromosome: Every somatic cell has chromosomes dictating certain properties. Chromosomes come in 23 sets of 2 in humans.

Haploid cell: Cell the contains a single set of chromosomes.

Diploid cell: Cell that contains two sets of chromosomes.

Triploid cell: Cell that contains three sets of chromosomes.

Meiosis: Meiosis separates one diploid cell into four haploid cells. It has phases: Prophase I, Pro-metaphase I, Metaphase I, Anaphase I, Telophase I, Prophase II, Pro-metaphase II, Metaphase II, Anaphase II, and Telophase II. In prophase I the two chromosomes mix and intangible with each other. The remaining phases are all pretty similar to their mitosis counterpart with the same name.

Allele: Variant of a gene. You get one from each of your parents for every gene.

Phenotype: Observable effects of an individual's genotype. Dictated by their alleles.

Chapter 14

Homozygous: A homozygous gene is a gene with two of the same alleles.

Heterozygous: A heterozygous gene is a gene with two different alleles.

Dominant allele: A heterozygous gene will adopt this allele's trait.

Recessive allele: A heterozygous gene will not adopt this allele's trait. A recessive allele can only effect an organism by being part of a homozygous gene.

Pedigree: Record of a certain gene in a family.

Genetic disorder: Disease inherited from parents. Usually (but not always) in the form of a recessive allele.

Carrier: Homozygous organism with one recessive allele of a genetic disorder. The carrier usually won't be affected by the disorder themselves, but if mating with another carrier, can potentially give the disorder to their offspring.

Epistatis: When a second gene's presence will affect a different gene.

Chapter 15

Wild type: The most commonly appearing allele of a gene.

Mutant type: The non-wild type allele.

Sex linked genes: Genes that are located exclusively on either the x or y chromosome. Called x-linked and y-linked genes respectively.

X linked genes: X linked recessive alleles can be passed down to family members of both sexes, but will only affect males.

Parental type: Same allele as a parent.

Recombinant type: different allele to both parents.

Chapter 16

Origin of replication: Site where DNA replication begins.

Replication bubble: Opening(s) created between the two strands of DNA. There is only one in the circular bacteria DNA. But in eukaryotic DNA, there can be hundreds.

Replication fork: Ends of the replication bubble.

Primer: RNA sequence created at the start of DNA replication, for polymerases to have something to add onto.

DNA polymerase: Enzymes that add new nucleotides to the 3' end of the DNA strand.

Leading strand: A strand of DNA being synthesised from the origin, in a 5' to 3' direction.

Lagging Strand: A strand separated into Okazaki fragments, synthesised towards the origin, in a 5' to 3' direction.

Helicase: Unwinds the double helix at the replication fork.

Single strand binding protein: Stabilises DNA strands by binding to them.

Topoisomerase: Relieves strain on the replication fork.

Primase: Creates the RNA primer.

DNA pol III: DNA polymerase that synthesises new nucleotides to the strand.

DNA pol I: DNA polymerase that removes and replaces the primer with nucleotides.

Ligase: Joins Okazaki fragments. Also connects the primer replacement to the rest of the strand.

Histones: Proteins that help keep DNA contained by allowing it to wrap around them.