Heredity and Molecular Biology Lecture Review

Comprehensive flashcards covering genetics, heredity, DNA molecular structure, protein synthesis, and cell division processes (Mitosis and Meiosis).

Incomplete Dominance

A heterozygous phenotype is somewhere between the two homozygous parents, blending.

Interphase

The portion of the cell cycle between two rounds of mitosis

Prophase

First phase of mitosis, in which the replicated DNA condenses into chromosomes, the nuclear membrane begins to disintegrate, and spindle fibers begin to form

Anaphase

Third phase of mitosis, in which the spindle fibers pull sister chromatids toward each end of the cell

Metaphase

Chromosomes align along the equator of the cell

Telophase

Fourth phase of mitosis, in which the spindle disappears and a nuclear membrane forms around each cluster of sister chromatids

DNA polymerase

Enzyme that assembles individual nucleotides into a new complementary strand of DNA using a template

RNA polymerase

Enzyme that transcribes DNA

Codominance

Both alleles of a gene are expressed completely; neither is dominant or recessive.

Trait

Distinguishing characteristics that are inherited from parent to offspring.

Homologous chromosomes

Pairs of matching chromosomes.

Autosomes

Chromosomes containing genes not directly related to the sex of an organism.

Sex chromosomes

Chromosomes containing genes that control the development of sexual characteristics ($XX$ female, $XY$ male).

Antigen

Protein markers on the surface of a red blood cell that determines the blood type of a person.

Antibodies

Proteins made by the immune system that attack foreign antigens.

Monohybrid Cross

Examines the inheritance of only ONE specific trait.

Dihybrid Cross

Examines the inheritance of only TWO specific traits.

Genotype

Genetic makeup, written with a combination of letters.

Carrier

A person that holds the abnormal allele in their DNA; heterozygotes for a recessive trait who do not have the disease.

Parental generation (P)

Pure bred, true-breeding parents (e.g., $rr \times RR$).

First filial generation (F1)

Offspring of the pure bred parents, which are always heterozygous ($Rr \times Rr$).

Second filial generation (F2)

Offspring of the F1 Generation.

Phenotype

The observable physical expression of an organism’s genetic makeup written with descriptive words.

Homozygous

When both chromosomes have identical alleles for a gene.

Heterozygous

When chromosomes have two different alleles for a gene.

Pedigree

A visual chart that depicts a family history or the transmission of a specific trait.

Gametes

Sex cells (sperm, ovum) through which DNA is passed onto offspring.

Punnett Square

A grid system for predicting all possible genotypes resulting from a cross.

Karyotype

A picture of a person’s chromosomes organized by numbers.

Allele

Alternative forms of a gene found at the same location on a chromosome.

Universal donor

Type O blood, because it does not have any antigens.

Universal recipient

Type AB blood, because it doesn’t have any antibodies.

Chargaff

Discovered that the amount of adenine equals thymine ($A=T$) and guanine equals cytosine ($G=C$).

Franklin

The scientist who took a picture of DNA.

Wilkins

Suggested that DNA had a double helix structure.

Nucleotide

The building block of nucleic acids consisting of a five-carbon sugar, one or more phosphate groups, and a nitrogenous base.

Purine

A bulky nitrogenous base with a double ring, including guanine and adenine.

Pyrimidine

A small nitrogenous base with a single ring, including thymine and cytosine.

Central Dogma

The concept that DNA makes RNA, involving replication, transcription, and translation.

Replication

The process occurring in the nucleus during the synthesis phase where DNA replicates using DNA helicase and DNA polymerase.

Transcription

The first step of gene expression where genetic information from DNA is copied to produce a complementary strand of mRNA in the nucleus.

Translation

The second step of gene expression occurring in the cytoplasm where mRNA is decoded by a ribosome to build a protein.

Semiconservative

Using a parental strand to make a new one during DNA replication.

Antiparallel

Refers to the two strands in DNA running in opposite directions ($5'$ to $3'$ and $3'$ to $5'$).

Okazaki fragments

Short pieces of DNA that make up the lagging strand, which is built in the opposite direction of the leading strand.

Exons

An 'expressed' or protein-coding sequence that is retained during messenger RNA splicing.

Introns

An 'intervening' sequence that is removed from an RNA molecule during splicing.

Codon

A sequence of three nucleotides in mRNA that tells the ribosome where to start/end protein assembly and which amino acids to use.

Anticodon

Three nucleotides in a transfer RNA (tRNA) molecule that pair specifically with a codon in mRNA.

Point mutation

A permanent change in genetic makeup caused by the substitution of a single nucleotide for another.

Interphase

The stage of the cell cycle where the cell replicates its DNA and organelles and grows; includes $g1$, $S$, and $g2$ phases.

Mitosis

The division of somatic cells in eukaryotic organisms producing two identical daughter cells.

Cytokinesis

The division of the cytoplasm that occurs after telophase; not part of mitosis.

Cleavage furrow

The structure that forms in animal cells during cytokinesis to pinch the cell in half.

Cell plate

The structure that forms in plant cells during cytokinesis between the two daughter nuclei.

Malignant tumor

A dangerous, fast-growing mass of cells able to break off and travel in the bloodstream.

Metastasis

When cancer cells break off from a tumor and travel through the bloodstream to end up anywhere in the body.

Cyclins and kinases

Proteins responsible for controlling the checkpoints within the cell cycle.

Apoptosis

Programmed cell death essential for development and removing old or infected cells.

Meiosis

The division of sex cells that involves two divisions and produces four genetically unique haploid daughter cells.

Haploid cell ($n$)

A cell containing one set of chromosomes ($23$ in humans), typical of gametes.

Diploid cell ($2n$)

A cell containing two sets of chromosomes ($46$ in humans), typical of somatic cells.

Crossing over

A process where homologous chromosomes break at identical locations and rejoin opposite partners during meiosis, mixing inherited genes.