Human Heredity Study Guide (Topics 1-4)

Vocabulary practice flashcards generated from the Human Heredity Unit I Study Guide covering DNA, genetics, cell organelles, cell division, and inheritance.

Gene (Location & Structure)

A short stretch of DNA located on a chromosome that holds directions for linking together various amino acids to produce a polypeptide.

Chromosome

A strand of DNA densely coiled around organizing proteins, located within cells.

Polypeptide

A long chain of amino acids with its own unique amino acid sequence.

Protein

A molecule composed of one or more folded polypeptides that plays vital roles in body health, functioning, and physical appearance.

Gregor Mendel

An Augustinian monk who conducted garden pea plant breeding experiments in the mid 1800s to establish basic principles of inheritance.

Blending Hypothesis

A pre-Mendelian hypothesis popular prior to Mendel stating that traits from the mother and father become irreversibly blended in offspring.

Heritable Factors

Particulate units of inheritance proposed by Mendel that do not blend in offspring and can be passed to the next generation in undiluted form.

Mendel's Paper Publication Date

1866, summarizing his work on inheritance using garden pea plants.

Francis Crick and James Watson

The English scientist and American scientist who built the first accurate 3-dimensional model of the DNA molecule in 1953.

DNA Model Year

1953, the year Watson and Crick built the accurate 3D model of DNA.

Double Helix

The 3-dimensional shape of a single DNA molecule, composed of two parallel strands of nucleotides bonded to one another.

Nucleotides

The basic building blocks of a DNA molecule.

DNA Nucleotide Symbols

A, G, C, and T.

Number of Amino Acid Types

20 different types used to build polypeptides.

Collagen Structure

Consists of three intertwined polypeptides forming strong rod-like structures.

Collagen Function

Lends tensile strength to skin and connective tissues such as bones, tendons, and ligaments.

Hemoglobin Structure

Four folded polypeptides brought together to resemble a four-part serving dish, each part containing a special unit for binding oxygen.

Hemoglobin Function

Enables red blood cells to carry many oxygen molecules at one time.

Active Site

A uniquely shaped pocket on the surface of an enzyme that provides a perfect fit for binding specific reaction molecules.

Enzyme Function

Speeds up specific chemical reactions in the body.

Cell Transport Proteins

Proteins embedded in cell membranes often shaped like hollow tunnels with unique interiors to allow specific nutrients or chemicals to pass.

Mutation

An alteration in the nucleotide sequence of a DNA gene.

Sickle Cell Anemia Cause

A mutation in the gene coding for hemoglobin, producing malformed hemoglobin molecules that crystallize into rigid rods.

Sickle Cell Anemia Symptoms

Fragile sickle-shaped red blood cells clogging blood vessels, causing muscle and joint damage, as well as organ failure.

Human Genome Project Establishment

Established in 1990 by the U.S. Department of Energy and the National Institutes of Health.

Human Genome Size

3 billion pairs of nucleotides.

Human Genome Project Completion Announcement

April 2003, when scientists completed nucleotide sequencing of the entire human genome.

Approximate Number of Human Genes

Most of the 21,000 human genes have been identified, sequenced, and mapped.

Prokaryotic Cell Characteristics

Smaller cell design lacking membrane-bound organelles with DNA floating loose in the cytosol.

Eukaryotic Cell Characteristics

Larger, complex cell design with DNA held in multiple chromosomes within a nucleus and containing membrane-bound organelles.

Prokaryotic Organism Example

Bacteria.

Eukaryotic Organism Examples

Multicellular organisms (animals, plants, fungi) and single-celled non-bacteria like amoebas and yeast.

Plasma Membrane Composition

Primarily composed of two layers of phospholipid molecules (phospholipid bilayer).

Plasma Membrane Transport Proteins

Proteins embedded in the membrane that assist specific substances across that cannot cross the phospholipid bilayer on their own.

Recognition Proteins

Proteins unique to each individual that allow the immune system to recognize its own cells and distinguish them from foreign cells.

Glycoproteins

Recognition proteins that have a short chain of sugar molecules bonded to them. The function is to assist in cell recognition and signaling.

Receptor Proteins

External cell membrane proteins uniquely shaped to receive specific chemical signals, allowing cellular communication.

Insulin Receptor Function

Binds insulin hormone to cause the receiving cell to take up glucose (sugar) more rapidly.

Nucleus

Cell organelle surrounded by a double-layered nuclear envelope that holds almost all of a cell's DNA and regulates cell activities.

Nuclear Envelope

Two layers of membrane surrounding the nucleus containing tiny pores for passage of small molecules between the nucleus and cytosol.

Messenger RNA (mRNA)

A nucleic acid built inside the nucleus using a DNA gene as a template, which exits through a nuclear pore into cytosol.

Ribosome Function

Attaches to mRNA in the cytosol and translates its message to assemble a polypeptide one amino acid at a time.

Endoplasmic Reticulum (ER)

An elaborate network of membranous channels snaking through the cytosol that produces molecules intended for secretion or cell use.

Rough Endoplasmic Reticulum (Rough ER)

Flattened channels studded with ribosomes on its outer surface, responsible for producing proteins intended for cell secretion.

Smooth Endoplasmic Reticulum (Smooth ER)

Skinny pipe-like channels lacking ribosomes, responsible for producing lipid (fatty type) molecules.

Golgi Apparatus

A stack of flattened membranous sacks located between ER and plasma membrane that receives, chemically modifies, and labels ER products before secretion.

Vesicles

Tiny bubbles of membrane that transport cellular products between organelles and fuse with plasma membranes for secretion.

Lysosomes

Vesicles containing digestive enzymes that serve as cellular recycling centers to break down excess materials, waste, damaged organelles, and microorganisms.

Pre-programmed Cell Death (Lysosomal Role)

Simultaneous bursting of multiple lysosomes within a cell during development causing self-digestion, such as removing webbing between human fetal fingers.

Mitochondria Function

Organelles that convert energy stored in food molecules into ATP.

ATP

A form of cellular energy that directly drives almost all energy-requiring cell processes such as growing, dividing, and transporting materials.

Semi-independent Organelles

A term describing mitochondria because they contain their own loops of DNA and tiny ribosomes, allowing self-replication within cells.

Maternal Inheritance of Mitochondria

The principle that a person inherits all of their mitochondria strictly from their mother.

Cytoskeleton

An elaborate network of protein fibers beneath the plasma membrane and throughout cytosol that reinforces cell shape and anchors organelles.

Flagella

Long single or few cellular appendages used for locomotion, such as the tail on male sperm cells.

Cilia

Multiple shorter cellular appendages that beat in unison to propel mucus and trapped debris away from lungs along the respiratory tract.

Cystic Fibrosis Cellular Malfunction

Malformed chloride ion transport proteins in plasma membranes preventing normal mucus secretion.

Cystic Fibrosis Symptoms

Unusually thick sticky mucus clogging respiratory, reproductive, and digestive tracts, leading to breathing difficulty, lung infections, and stunted growth.

Tay-Sachs Disease Cellular Malfunction

Defect in a lysosomal enzyme required to break down a lipid that accumulates in brain cells.

Tay-Sachs Disease Symptoms & Prognosis

Lipid buildup in brain cells causing blindness, seizures, brain damage, and loss of motor control; fatal usually by age 5 or 6.

Mitochondrial Myopathies Cause

Mutated or missing genes in mitochondrial DNA leading to ineffective ATP production.

Mitochondrial Myopathies Symptoms

Muscle weakness, extreme fatigue, and visual problems affecting muscles, eyes, kidneys, and brain.

Stem Cell

An unspecialized cell with the potential to give rise to different specialized cell types.

Embryonic Stem Cells

Stem cells derived from early human embryos capable of giving rise to virtually any cell type.

Adult Stem Cells

Tissue-specific or somatic stem cells with limited potential (e.g., bone marrow stem cells forming blood cells but not nerve cells).

Induced Pluripotent Stem Cells

Laboratory-created stem cells used in research and clinical trials.

Mitosis Purpose

Growth, development, and replacement of cells lost from tissues due to injury or wear and tear in multicellular organisms.

Human Zygote

A fertilized egg that undergoes repeated mitotic divisions to develop into an embryo, fetus, child, and adult.

Cells in the Cell Cycle

Dividing cells capable of undergoing mitosis, including epithelial cells (epidermis, tract linings), bone marrow cells, and blood vessel linings.

Cells Pulled Out of the Cell Cycle

Nondividing specialized cells, such as neurons and certain muscle fibers.

Chromatin Fibers

Loosely coiled DNA fibers wrapped around organizing proteins in non-dividing cell nuclei.

Chromatin

The entire collection of loosely coiled chromatin fibers within the nucleus.

Chromosomes (Dividing Cells)

Highly condensed, tightly coiled sausage-like structures of DNA and organizing proteins seen during cell division.

Interphase

The phase of the cell cycle between cell divisions, subdivided into G1, S, and G2 stages.

G1 Stage

First stage of interphase where a newly formed cell takes up nutrients and grows larger.

S Stage

Middle stage of interphase during which all cellular DNA is replicated.

G2 Stage

Last stage of interphase during which enzymes and proteins necessary for guiding mitosis are produced.

Cell Division Phase (Mitotic Phase)

Phase encompassing nuclear division (mitosis) and cytoplasm division (cytokinesis).

Mitosis Stages (Order)

Prophase, Metaphase, Anaphase, Telophase.

Prophase (Mitosis)

Stage where chromatin condenses into chromosomes, nuclear envelope breaks down, and spindle apparatus forms.

Metaphase (Mitosis)

Stage where replicated chromosomes line up along the equator of the cell.

Anaphase (Mitosis)

Stage where sister chromatids separate at centromeres and migrate toward opposite poles.

Unreplicated Chromosome

A separated sister chromatid migrating toward a pole during anaphase.

Telophase (Mitosis)

Stage starting when unreplicated chromosomes reach opposite poles, uncoil into chromatin, and nuclear envelopes reform.

Cytokinesis

Division of cytoplasm overlapping with telophase via a contractile fiber ring pinching the cell into two smaller cells.

Sister Chromatids

Identical copies of the same genetic information joined within a replicated chromosome.

Centromere

A constricted region holding two sister chromatids together.

Kinetochores

Structures located at centromeres on sister chromatids that attach to spindle fibers to facilitate migration.

Spindle Fibers Function

Align replicated chromosomes at the equator during metaphase and guide separated chromosomes toward poles during anaphase.

Gametes

Reproductive cells (sperm for males, ova for females) produced by meiosis.

Testes

Male reproductive organs where meiosis and spermatogenesis occur.

Ovaries

Female reproductive organs where meiosis and oogenesis occur.

Diploid Cell

A cell containing two full sets of chromosomes (two of each type).

Haploid Cell

A cell containing only one set of chromosomes (one of each type).

Human Diploid Chromosome Number

46 chromosomes.

Human Haploid Chromosome Number

23 chromosomes.

Homologous Chromosomes

A pair of chromosomes in a diploid cell of the same shape and size that carry genes influencing the same traits.

Origin of Homologous Pairs

One chromosome of each homologous pair is inherited from the mother, and the other from the father.

Homologous Pair Non-Identity

Homologous chromosomes are not identical because genes come in different versions (alleles) inherited from each parent.

Meiosis Stages (Order)

Meiosis I (Prophase I, Metaphase I, Anaphase I, Telophase I) followed by Meiosis II (Prophase II, Metaphase II, Anaphase II, Telophase II).