intro
Genetics is the study of genetic information, genetic variation, and heredity in organisms.
A genome is all the genetic information of an organism.
Heredity is the set of biological processes by which particular characteristics are transmitted from parents to their offspring.
Genetic information ordered by size:
- A nucleotide (a letter)
- A codon (three letters)
- A gene
- A chromosome
- A genome
genetic information
A genotype is a part of DNA that codes for a trait in an organism.
A phenotype is an observable trait.
The type of cell needed to use in sexual reproduction to form a zygote is called a gamete.
An allele is a variant of a gene with a unique genotype. However, two alleles can have the same phenotype.
When an organism has both a dominant and recessive allele for a trait, the organism is heterozygous for the trait. In contrast, if same then is homozygous for the trait.
An organism has the same number of chromosomes in each of its cells. This number is called the diploid number.
If the number of chromosomes in an individual is abnormal, it is called aneuploidy, meaning chromosomal disorders.
To do sexual reproduction, an organism has to produce gametes. a gamete has a haploid number of chromosomes.
Chromosomes that determine the sex of the organism are called sex chromosomes or allosomes, and those that do not are called autosomes.
a Mendelian gene is a section of a chromosome that corresponds to a phenotype in the organism
A gene is a length of DNA that contains the coded instructions for building a gene product, which is usually a protein.
Genotype is the combination of alleles an individual has for a given gene locus.
Phenotype is the physical expression of a trait and is influenced by the genotype.
Recessive traits are those which are not expressed in the phenotype of a heterozygote.
Dominant traits are expressed in the phenotype of a heterozygote.
Some traits are incompletely dominant to others, in which case neither allele is fully expressed in the phenotype of a heterozygote. Some traits are codominant, meaning that both alleles are fully expressed in the phenotype of a heterozygote.
Some gene loci have more than just two alleles.
Alleles are assigned symbols; a capital letter for a dominant trait and a lower case letter of the same letter for the recessive trait.
The alleles for X-linked traits are shown as a superscript to an X. The alleles for incompletely dominant and codominant traits are superscripted to differentiate between them.
A genotype is a section of DNA that can be expressed into phenotypes (observable traits).
the genotype of an organism is its complete set of genetic material.
”genotype” may also refer to a genetic trait in an organism
The diploid number is the number of chromosomes in an organism.
Somatic cells are the bodily cells of an organism.
The diploid number in humans is 46.
Chromosomes that determine the sex are allosomes (also sex chromosomes) and chromosomes that do not are autosomes.
an allele is a variant of a gene with a unique genotype, and when the genotype is expressed into unique phenotypes
a dominant allele can have their genotype expressed by overriding recessive alleles
for example, a genotype for brown eye color is dominant, and a genotype for blue eye color is recessive
this can be expressed in a Punnett square
heterozygous means carrying both genotypes, but the dominant one is expressed and the other isn’t
homozygous means that both genotypes are the same
Interphase is the phase before mitosis, in charge of DNA replication.
The aim of a cell doing mitosis is to divide into two identical cells.
The phases of mitosis in are prophase, metaphase, anaphase, telophase and cytokinesis.
During prophase of mitosis, the chromosomes condense and centrosomes move to opposite poles of the cell. During metaphase of mitosis, the chromosomes move and line up at the center of the cell and attaches to spindle fibers. During anaphase of mitosis, chromosome pairs are split by spindle fibers and moved to different directions. During telophase of mitosis, chromosomes start to de-condense, nuclear membrane starts to re-form. During cytokinesis of mitosis, the cell membrane splits.
The aim of meiosis is to divide into 4 genetically different gametes (which are haploid cells).
Before meiosis we have a diploid cell and after we have four haploid cells.
The Golgi apparatus does sorting, packaging, processing and modification of proteins.
The ribosome does translation in protein synthesis.
The mitochondria does cellular respiration.
Organelles that all eukaryotic cells have are cell membrane, ER, Golgi apparatus, nucleus, vacuole, and ribosome.
https://en.wikipedia.org/wiki/List_of_organisms_by_chromosome_count