Concept 1, 2, 3 Mendelian Genetics, Complex Ingeritance Patterns, and Mutations and Pedigrees (Biology)

Gene

Section of DNA that provides the instructions for making a protein

Alleles

Different versions of the same gene

Homologous chromosomes

The matching chromosomes from your mom and dad

Homozygous

the same type of allels

Dominant

Allele that will always have that trait expressed, if present

Recessive

Allele that will only able the trait expressed when the dominating allele is not present

Genotype

The actual alleles inherited for a gene

Phenotype

The physical traits/characteristics seen in an organism

Punnett square

Diagram that shows the probability of inheriting traits from parent with certain genes

Monohybrid cross

A cross between two organisms looking at one trait

Dihybrid cross

A cross when looking at the likelihood of inheriting two traits together

Law of Dominance

A dominant allele will express itself over a recessive allele

Law of Segregation

When chromosomes separate in meiosis only one form each pair should end up in each gamete

Law of Independent Assortment

When chromosomes line up and separate in meiosis it happens completely randomly

Chromosome Theory of Inheritance

Since genes are located on chromosomes, how the chromosomes behave during meiosis will determine inheritance

Epistasis

When one gene overshadows all others

Carrier

Someone who carries a recessive allele but doesn’t show the trait due to having a dominant allele to mask over it

Incomplete Dominance

heterozygous genotype yields a phenotype that is a blend of the other two traits.

Codominance

heterozygous genotype yields a phenotype that

shows both of the other traits fully and separately.

Multiple alleles

more than 2 versions of 1 gene

Polygenic inheritance

more than 1 gene determines a trait. (blood type)

Linked genes

genes that are physically located close together on the same chromosome are often inherited together

Sex-linked traits

genes for traits located on sex chromosomes

Mutation

Any change in DNA

Mutagen

Chemical that can cause a mutation in DNA

Translocation

A chromosome mutation that results when pieces of non-homologous chromosomes exchange segments during crossing over

Nondisjunction

A chromosome mutation that results from chromosomes not separating correctly during anaphase, causing the wrong number of chromosomes in the resulting gametes

Pedigree

Chart used to trace a trait/disease through a family tree

Gene mutation

A change to the organically DNA sequence affecting a single gene

Chromosome mutation

A change to a section of a chromosome that affects the number and/or location of multiple genes

Point mutation

One nucleotide is substituted for another

Frameshift mutation

One nucleotide gets added to or deleted from the sequence, causing all subsequent codons to be affected due to the change in the reading frame

Autosomal recessive

males and females must inherit 2 recessive alleles with the disease in order to show it (cystic fibrosis)

Sex-Linked (genetic mutations)

males only need to inherit 1 affected X, where as females must inherit the genes on both of their X chromomes to show it

Autosomal chromosomal

Mutation on an autosome. (downs syndrome)

Autosomal Dominant

Males and Females only need to inherit 1 dominant allele with the dies ease in order to show it. (huntington’s disease)

Sex chromosomal

mutation on sex chromosomes. (turner syndrome)