Genetics Flashcards
(63 cards)
Genes
Hereditary units of DNA transmitted from one generation to another; code for proteins
Locus
The specific location of a gene on a chromosome vs. genetic marker isn’t as exact (zone of a chromosome)
Alleles
Different versions of a gene; humans have 2 alleles for each autosomal gene
Chromosomes
Structure composed of genes located in nucleus of a cell
Homologous chromosomes
Have the same genes at the same loci, one maternal and one paternal
Genome
The genetic information contained in the cells, on the chromosomes, for a particular species
Mutation
A change in some part of the DNA code. Can be:
- Spontaneous
- Induced by exposure to mutagenic chemicals or radiation
Autosome
Any chromosome that is not a sex chromosome (humans have 22 pairs of autosomes)
Haploid number
the number of chromosomes in sex cells/gametes (n=23)
Diploid number
the total number of chromosomes in somatic cells (2n=46)
Somatic chromosomes
Autosomes
Sex chromosomes
Allosomes
- Males have one morphologically dissimilar pair (heteromorphic), labeled X and Y. Genetic factors on the Y determine maleness
- Females have two morphologically similar X’s
Karyotype
The characterization of the chromosomal complement of an individual or a species, including number, form, and size of the chromosomes.
Mitosis
- The process by which all somatic cells replicate and become descendants of one original cell
- One exact copy of each chromosome is made and distributed through the division of original cell into two daughter cells
Meiosis
- The process by which gamete cells are produced (egg and sperm)
- Resulting gametes have 23 new chromosomes, with new combos of the original maternal and paternal copies
- Occurs only in specialized germ cells of gonads
- 2 consecutive cell divisions producing cells with half the original chromosome number
- -> Diploid 2n–>haploid n
Genotype
All of the alleles of an organism
- Homozygous: contains the same allele @ a single locus
- Heterozygous: contains 2 different alleles @ a single locus
Phenotype
a measurable trait an organism has
-i.e. hair color, eye color, blood type
Dominant allele
Phenotype can be seen in both the heterozygote and homozygote
Carrier
Heterozygous individual with a recessive alley that’s hidden from phenotypic view by the dominant, normal allele
Ex: Cystic Fibrosis
Recessive allele
Produces this phenotype only when its paired allele is identical
Single Gene Disorders (Mendelia Disorders) Classification
- Autosomal or x-linked
- Dominant or recessive pattern
Mendel’s Principle of segregation
One parent has 2 copies of a gene for trait, but transmits o only one via a gamete
Codominance
When two alleles for a trait are equally expressed
Ex: AB blood type
incomplete dominance
Heterozygotes have phenotypes that have both alleles visible as a blend (makes a third phenotype)
Ex: wavy hair, skin color