Human Genetics Flashcards

Flashcards for Human Genetics

Chromatin

The material of which chromosomes are made, consisting of DNA and protein.

Chromosome

A thread-like structure of nucleic acids and protein that carries genetic information in the form of genes.

Nucleic acids

A structural unit of nucleic acid in the double helix strand of DNA.

Genes

Sections of DNA that serve as instruction manuals for protein synthesis.

Gene

A section of a DNA molecule that provides guidelines for specific traits.

Gene Locus

The position or location on the DNA strand at which a specific gene may be found.

Allele

A variation of a specific gene.

Multiple alleles

When more than 2 different alleles exist in the population for a single trait.

Homozygous

When the pair of alleles are the same, the organism is for that trait.

Heterozygous

When the pair of alleles are different, the organism is for that trait.

Genotype

The specific alleles an individual possesses.

Phenotype

The visible trait in an individual. Which is determined by which allele the cell actually reads to express the trait.

Dominant/Recessive and examples

A specific allele, if present, will be activated. Brown/Blue or Green/Blue, tongue rolling, widows peak The dominant allele masks the effect of a recessive allele in a heterozygous genotype, leading to the expression of the dominant trait.

Codominancy and example

Different alleles will both be activated independently. AB blood type

Incomplete Dominancy and example

Different alleles will be activated simultaneously, resulting in a blended phenotype. sickle cell trait

Polygenics examples

Multiple chromosomes contain genes for the same trait. skin color, hair color, eye color, height

dominance modification and examples

alleles at one locus modifies a dominant gene at another locus, eye and hair color

epistasis

a recessive pair at one locus blocks a dominant allele at another locus resulting in altered phenotypic expression.

sex influence and examples

phenotype shown for a specific allele will be different for males and females, pattern baldness and parkinsons disorder

environmental influence and example

phenotype may be modified by changes in the environment, eye color

sex linked traits

traits for which the gene locus is on chromosome 23 (x or y), x is longer than y, if trait is found on x it may not occur on y

sex linked traits for males exception and examples

in males, there is no paired alleles, one allele will always determine phenotype, hemophilia and color blindness (red/green)

traits of sex linked traits

most often seen in males, often skips a generation, female must be a carrier or have the gene for daughters to have it, if male has it all daughters will be carriers or have trait, if female has trait all sons will have it