Chapter 29 Heredity Flashcards

Flashcards on Heredity, Genetics, and Inheritance

DNA

The genetic material composed of individual nucleotides.

Genes

Specific sequences of nucleotides on DNA that carry the code for the manufacture of specific proteins.

Chromosomes

Condensed or coiled DNA along with proteins; DNA takes on this condensed configuration at the time of cell division.

Autosomes

22 pairs of chromosomes with general information.

Sex chromosomes

1 pair of chromosomes which carry information about sex as well as some other traits; designated X and Y.

Allele

The various forms of a given gene.

Homozygous

Having two alleles that are the same.

Heterozygous

Having two alleles that are different.

Dominant allele

An allele that is always expressed even if the second allele is different.

Recessive allele

An allele that is always masked or hidden if the dominant allele is present.

Genotype

An organism’s specific genetic make-up.

Phenotype

Physical characteristics of an organism such as blue eyes, brown hair, etc.

Karyotype

Chromosomes arranged in pairs according to their size, shape and general appearance; used to diagnose chromosomal abnormalities.

Dominant/recessive inheritance

One allele is completely dominant (is expressed) and one allele is completely recessive (is not expressed).

Incomplete dominance

Neither allele is completely dominant over the other; usually expressed as an intermediate trait between the two alleles.

Codominance

Neither allele is dominant over the other and, if both alleles are present, they are both expressed.

Polygenic inheritance

More than one gene contributes to the expression of a trait.

Punnett square

A simple technique for predicting the probability of inheriting a trait.

Pedigree

Charts that trace a genetic trait through several generations in order to assess risk.

Crossing over

Occurs during prophase of meiosis I; chromosomes in synapsis may exchange pieces and reshuffle the genetic material.

Spontaneous mutations

Happen for no known reason; usually caught and repaired by proofreading enzymes.

Deletions

A piece of a chromosome is lost.

Substitutions

One nucleotide is substituted for another.

Additions

Additional nucleotides are added.

Frame shifts

If nucleotides are added or deleted, then the sequence of nucleotides in the DNA triplets will be changed after the addition or deletion; this leads to misinformation after the mutation.

Sex-Linked Inheritance (or X-linked)

Traits that are carried on the X chromosome.

The Human Genome Project

Joint public and private sector project to map the entire human genome, nucleotide by nucleotide.