Genetics, Heredity, and Molecular Biology Review

Comprehensive vocabulary flashcards covering DNA structure, cell division, Mendelian and non-Mendelian genetics, chromosomal disorders, pedigrees, and biotechnology.

DNA (Deoxyribonucleic acid)

Stores genetic information used to build and maintain an organism.

Nucleotide

The structural unit of DNA composed of three parts: a phosphate group, a deoxyribose base, and a nitrogenous base.

Purines

Double-ringed nitrogenous bases, which include Adenine ($A$) and Guanine ($G$).

Pyrimidines

Single-ringed nitrogenous bases, which include Thymine ($T$) and Cytosine ($C$).

Mitosis

Cell division that produces two genetically identical daughter cells.

Heredity

The passing of genetic information from parent to offspring.

Gene

Inherited information that carries a code for specific traits or functions.

Locus

The site on a chromosome that a specific gene occupies.

Chromosome

A structure made of DNA and proteins that carries genes.

Haploid ($n$)

Having one set of chromosomes ($23$ chromosomes in humans).

Diploid ($2n$)

Having two sets of chromosomes ($46$ chromosomes in humans).

Meiosis

A two-stage cell division process in which the resulting daughter cells have half the number of chromosomes as the parent cell, resulting in gametes.

Homologous chromosomes

Matching pairs of chromosomes that are similar in size and carry information for the same gene.

Reduction division

The division in meiosis I when a diploid cell splits into $2$ haploid cells.

Tetrad

Two paired homologous chromosomes.

Crossing over

The process where homologous chromosomes exchange corresponding DNA segments in prophase I.

Gametogenesis

The production of sex cells in animals.

Spermatogenesis

The production of sperm cells.

Oogenesis

The production of egg cells, in which cytoplasm does not divide evenly, producing one ovum (egg cell) and $3$ polar bodies that die.

Karyotype

An organized picture of chromosomes arranged in pairs, showing $46$ chromosomes ($23$ pairs) in humans.

Autosomes

Non-sex chromosomes; in humans, chromosome pairs $1\text{–}22$.

Non-disjunction disorders

Disorders resulting from the failure of homologous chromosomes to move to opposite sides of the cell during meiosis, leading to an abnormal amount of chromosomes in daughter cells.

Trisomy 21

Down Syndrome.

Trisomy 13

Patau syndrome.

Trisomy 18

Edwards syndrome.

Chromosomal Deletion

A mutation where a chromosome segment is lost.

Chromosomal Duplication

A mutation where a chromosome segment is copied.

Chromosomal Inversion

A mutation where a chromosome segment reverses direction.

Chromosomal Translocation

A mutation where a chromosome segment moves to another chromosome.

Insertion mutation

A mutation where extra DNA is inserted into a sequence.

Amniocentesis

A genetic test where a sample of amniotic fluid is collected before birth to test fetus cells for non-disjunction disorders.

Chronic villus sampling (CVS)

A genetic testing procedure where a sample of placental tissue is collected.

Monohybrid Cross

A genetic breeding experiment that tracks the inheritance of a single trait between two parent organisms that have different variations of that trait.

Alleles

Different forms of genes.

Law of Segregation

The law stating that the two alleles for a gene separate during gamete formation (meiosis) so each gamete receives one allele.

Genotype

The set of alleles or allele combination of an individual (e.g., $BB$, $Bb$, $bb$).

Phenotype

The traits an individual expresses (e.g., purple flowers).

Homozygous

A condition where two alleles are the same (e.g., $BB$ or $bb$).

Heterozygous

A condition where two alleles are different (e.g., $Bb$).

Dominant allele

An allele that determines the trait a heterozygous individual expresses (e.g., $B$).

Recessive allele

An allele that is not expressed in a heterozygous individual (e.g., $b$).

Punnett Square

A diagram used to predict possible genotypes of offspring.

Test cross

A cross used to determine if an individual showing a dominant trait is homozygous or heterozygous for that trait.

Complete dominance

A variation of inheritance where the dominant allele, if present, is fully expressed phenotypically.

Incomplete dominance

A pattern of inheritance where neither allele completely masks the other, producing an intermediate phenotype in the heterozygote (e.g., $C^W C^W$ = white, $C^R C^R$ = red, $C^R C^W$ = pink).

Codominance

A pattern of inheritance where both alleles appear in the offspring at the same time (e.g., $H^R H^R$ = red, $H^W H^W$ = white, $H^R H^W$ = roan).

Pedigree

A diagram that traces the inheritance of a certain trait through members of a family.

Autosomal Dominant

An inheritance pattern where one copy of a dominant allele on a non-sex chromosome is enough to show the trait.

Autosomal Recessive

An inheritance pattern where two recessive alleles on a non-sex chromosome are needed to show the trait.

X-linked dominant

An inheritance pattern where one dominant allele on the X chromosome is enough to show the trait.

X-linked recessive

An inheritance pattern where a recessive allele on the X chromosome causes the trait; males require $1$ copy ($XY$) and females require $2$ copies ($XX$).

Dihybrid cross

A cross that studies two traits at the same time, where each parent produces $4$ types of gametes in a $4 \times 4$ Punnett square.

The product law

The principle stating that the probability of two independent random events both occurring is the product of their individual probabilities (e.g., probability of having $2$ boys is $\frac{1}{2} \times \frac{1}{2} = \frac{1}{4}$).

Human Genome Project

An international collaboration ($1990\text{–}2003$) that mapped and sequenced human DNA to locate all genes on the human genome, identify gene functions, and study differences between people and species.

Gel electrophoresis

A technique that separates DNA fragments by size by applying an electric current to pull negatively charged DNA toward the positive electrode, causing shorter fragments to move faster and further.

Model Organisms

Certain species studied and compared to humans; for example, mice, which have a similar number of nucleotides and a comparable number of genes.

Genetic engineering

Directly changing an organism's DNA.

Gene therapy

Treating a disease by modifying genetic material.

Restriction enzymes

Enzymes that cut DNA at a specific sequence.

Sticky ends

Short exposed DNA overhangs produced after cutting that can pair with complementary DNA.

Plasmid

A small circular DNA molecule commonly found in bacteria.

Recombinant DNA

DNA formed by combining genetic material from different sources.

Vector

A carrier used to deliver DNA into a cell.

Target cell

The cell intended to receive genetic material.