Learn: Chromosomes to Genomes & Inheritance | Quizlet

Genome

The sum of all the genes in the cell of an organism.

Parental Allele Contribution

Each parent provides one allele of a particular gene to their offspring.

Phenotype

The outward physical appearance and expression of an organism's genes.

Genotype

The genetic make-up of an organism.

Parental (P) and Filial (F1, F2) Generations

Terms for original parent plants (P) and successive offspring generations (F1, F2).

Dominant vs. Recessive Alleles

Alleles where one is able to mask the expression of the other.

Homozygous Genotype

A genotype where both alleles are the same, such as TT or tt.

Heterozygous Genotype

A genotype where the two alleles are different, such as Tt.

Allele Letter Convention

Capital letters are used for dominant alleles and lowercase letters for recessive alleles.

Incomplete Dominance

When one trait is not fully dominant over the other, resulting in a blended intermediate phenotype.

Snapdragons Incomplete Dominance

Crossing pure-breeding red and white snapdragons produces a heterozygous pink phenotype.

Co-dominance

When both alleles in a heterozygous genotype are fully and simultaneously expressed.

Co-dominance in Cattle and Camellias

Shorthorn cattle showing both red and white hairs, or camellias showing red and white patches.

Environmental Factors on Phenotype

External conditions like light or food availability that influence allele expression.

Epigenetics

The study of how chemicals influence allele phenotypes without altering the DNA structure.

Epigenome

An organism's genes plus the chemical compounds attached to DNA that modify genome expression.

Epigenetic Modifications

Chemical changes not part of the genome sequence that affect how genes are expressed.

Gene Definition

An inherited DNA instruction containing the code for ribosomes to create a protein.

Human Gene Count

An estimated 25,000 different genes in the human genetic make-up.

Diploid Cells & Homologous Pairs

Chromosomes found as homologous pairs in diploid cells, with one allele per chromosome.

Meiosis and Chromosomes

Homologous chromosomes separate during meiosis so haploid gametes receive one chromosome per pair.

Haploid Gametes

Gametes that contain only one of each pair of chromosomes and one allele per gene.

Fertilization and Diploid Restoration

The fusion of gametes during fertilization that restores homologous pairs and two alleles per cell.

Monohybrid Cross

A genetic cross involving one pair of alleles of a particular gene.

Punnett Square

A grid tool used to predict parent genotypes, gametes, and F1/F2 cross outcomes.

Heterozygous Monohybrid Ratio

The predicted 3:1 phenotypic ratio in a simple dominant-recessive cross of two heterozygous parents.

Test Cross

A cross between an individual of unknown genotype and a homozygous recessive individual.

Test Cross Outcomes

Homozygous dominant gives 100% dominant phenotype; heterozygous gives a 1:1 dominant-to-recessive ratio.

Lethal Genes

Allele combinations that cause lethal phenotypes and alter predicted offspring ratios.

Lethal Yellow Mice

Crosses of heterozygous yellow mice producing a 2/3 yellow to 1/3 grey ratio due to lethal YY genotype.

Multiple Alleles

When a gene has more than two possible allele variations within a population.

Human ABO Blood Group Alleles

The multi-allelic system featuring type A (IA), type B (IB), and type O (i) alleles.

ABO Blood Group Dominance

Type A and B alleles are co-dominant, and both are dominant to type O.

Sex-Linked Genes

Genes carried on the X or Y sex chromosomes.

X vs. Y Linked Gene Functions

X carries non-sexual and female traits; Y carries maleness traits like testis development.

Non-Homologous Sex Chromosomes

X and Y chromosomes are not homologous, meaning X genes are not carried on Y.

Hemizygosity in Males

Having only one X chromosome, meaning any allele present determines the male's phenotype.

Female Carriers

Females having two X copies can carry a recessive trait without expressing it.

Ishihara Test Plates

Plates used to test for color vision deficiencies.

Red/Green Colour Blindness Alleles

XC for normal vision and Xc for red/green color blindness on the X chromosome.

Female Colour Blindness Genotype

A female must have two recessive c alleles (XcXc) to express color deficiency.

Male Colour Blindness Genotype

A male with an XcY genotype will be color deficient since he has only one X chromosome.

Pedigree Charts

Charts used by geneticists to trace the inheritance of characteristics and disorders across generations.

Autosomal Recessive Pedigree

Two unaffected parents have an affected child, can skip generations, and affected individuals are homozygous recessive.

Autosomal Dominant Pedigree

Does not skip generations; all children must have at least one affected parent.

X-Linked Dominant Pedigree

Affected father passes trait to all daughters; more females affected than males; does not skip generations.

X-Linked Recessive Pedigree

Mother passes trait to all sons; more males affected; can skip generations; female carriers common.

Dihybrid Cross

The genetic study of two different genes at the same time.

Independent Assortment

When genes on different chromosome pairs segregate independently during meiosis.

Dihybrid Test Cross

Crossing an unknown genotype with a homozygous recessive individual for both genes (aabb).

Dihybrid Test Cross Homozygous Outcome

Expected phenotypic ratio of 9:3:3:1 in the F2 generation when crossing a homozygous parent.

Heterozygous Dihybrid Test Cross Ratio

Expected phenotypic ratio of 1:1:1:1 when crossing a heterozygous dihybrid parent with a double recessive individual.

Linked Genes and Linkage Groups

Genes located on the same chromosome that do not assort independently, forming a linkage group.

Linked Gene Notation

Genotypes of gametes written together and fused gametes shown in fraction-like notation.

Crossing Over Process

The exchange of chromosome sections between non-sister chromatids of homologous chromosomes at Prophase I.

Crossing Over and Gene Distance

Linked genes close together have a lower chance of crossing over and are more likely inherited together.

Polygenic Inheritance

Characteristics controlled by the alleles of more than one gene, such as human height or skin color.

Continuous vs Discontinuous Variation

Continuous variation shows a smooth range of phenotypes, while discontinuous variation features distinct, separate phenotypes.

DNA Replication

The biological process by which a cell makes an identical copy of its DNA before cell division.

Transcription

The cellular process where a DNA sequence is copied into messenger RNA (mRNA) inside the nucleus.

Translation

The process where ribosomes decode mRNA to synthesize a specific polypeptide or protein chain.

Point Mutation

A genetic mutation that changes a single nucleotide base pair within a DNA sequence.

Mitochondrial Inheritance

The maternal transmission of DNA located inside mitochondria, which does not follow standard nuclear inheritance.