Bio Unit 3

BRCA 1/2

Genes that help repair damaged DNA and prevent uncontrolled cell growth. Mutations increase cancer risk.

Allele

An alternative version of a gene.

Homologous Chromosome

A pair of chromosomes with the same genes, one inherited from each parent.

n

The number of chromosomes in one complete set (haploid number).

Haploid

A cell with one set of chromosomes (n), such as a sperm or egg.

Diploid

A cell with two sets of chromosomes (2n), one set from each parent.

Gamete

A haploid reproductive cell (sperm or egg) that joins during fertilization.

Zygote

The diploid cell formed when two haploid gametes fuse during fertilization.

Meiosis I

The first division of meiosis; homologous chromosomes separate, reducing the chromosome number by half.

Meiosis II

The second division of meiosis; sister chromatids separate, producing four haploid cells.

Contact-dependent Signaling

Cell signaling that requires two cells to physically touch.

Local/Paracrine Signaling

A cell releases chemical signals that affect nearby cells.

Long-distance Signaling

Signals travel over long distances to communicate with distant target cells.

Receptor

A protein that binds a specific signaling molecule and triggers a cellular response.

Endocrine Signaling

Hormones travel through the bloodstream to affect distant target cells.

Nervous System

Uses electrical impulses and neurotransmitters to send rapid, targeted signals

Agonist

A molecule that binds to and activates a receptor, producing a response.

Antagonist

A molecule that binds to a receptor and blocks its activation.

Signal Transduction

The process of converting an external signal into a response inside a cell.

First Messenger

An extracellular signaling molecule that binds to a receptor.

Second Messenger

An intracellular molecule that relays and amplifies a signal inside the cell.

Kinase

An enzyme that adds phosphate groups to proteins or other molecules.

Phosphatase

An enzyme that removes phosphate groups from proteins or other molecules.

3 Mechanisms of Signal Termination

Signal molecule is removed, receptor is inactivated, or intracellular signaling molecules are inactivated

Hormones

Chemical messengers released by endocrine cells that travel through the blood to target cells.

Reuptake Transporters

Proteins that move neurotransmitters back into the releasing neuron, ending their signaling.

SSRI

Selective serotonin reuptake inhibitor; medication that blocks serotonin reuptake, increasing its availability outside neurons.

Pathogen

A disease-causing organism or infectious agent.

Virus

An infectious agent containing DNA or RNA that must use a host cell to reproduce.

Antigen

A molecule recognized by the immune system that can trigger an immune response.

Antibodies

Proteins made by B cells that specifically bind to antigens.

B Cells

Immune cells that can become plasma cells, which produce antibodies, or memory B cells.

Clonal Expansion

The rapid multiplication of immune cells after recognizing a specific antigen.

MHC Protein

A cell-surface protein that displays antigen fragments for T cells to recognize.

Cytotoxic T Cell

An immune cell that kills infected or abnormal body cells.

T Helper Cell

An immune cell that releases signals to activate and coordinate other immune cells.

Memory Cell

A long-lived immune cell that allows a faster response if the same antigen returns.

Vaccine

A preparation that trains the immune system to recognize a pathogen and develop immune memory.

Chromatin

DNA wrapped around proteins; the less-condensed form of genetic material in the nucleus.

Centromere

The chromosome region that holds sister chromatids together and helps attach the spindle.

Genome

The complete set of an organism's genetic material

Sister Chromatids

Two identical copies of a replicated chromosome joined at the centromere.

DNA Replication

The process of copying DNA before cell division so each daughter cell receives a copy.

Mitotic Spindle

A structure made of microtubules that separates chromosomes during cell division.

Centrosomes

Structures that organize microtubules and help form the mitotic spindle in animal cells.

Kinetochore Microtubules

Spindle fibers that attach to kinetochores and move chromosomes during division

Polar (Nonkinetochore) Microtubules

Spindle fibers that overlap and push the two poles of the cell apart.

Stages of Mitosis

Prophase, prometaphase, metaphase, anaphase, and telophase.

Cytokinesis

Division of the cytoplasm, separating one cell into two daughter cells.

Interphase

The period when a cell grows, performs normal functions, and replicates its DNA (G1, S, G2).

Cyclin

A regulatory protein whose levels rise and fall to help control the cell cycle.

Cyclin-dependent Kinase (CDK)

An enzyme activated by cyclins that regulates cell-cycle progression by phosphorylating proteins.

Oncogene

A gene that, when abnormally activated, can promote uncontrolled cell division.

Tumor Suppressors

Genes that slow cell division, repair DNA damage, or trigger cell death to prevent cancer.

Terminally Differentiated

A specialized cell that has reached its final form and typically no longer divides

Stem Cells

Undifferentiated cells that can self-renew and develop into specialized cell types.

Potency

A stem cell's ability to develop into different types of cells.

iPSC

Induced pluripotent stem cell; an adult cell reprogrammed to behave like a pluripotent stem cell.

Cancer

A disease in which abnormal cells grow and divide uncontrollably and may invade or spread.

Tumor

An abnormal mass of cells formed by excessive cell division.

Benign Tumor

A noncancerous tumor that does not invade nearby tissues or spread to distant sites.

Malignant Tumor

A cancerous tumor that can invade nearby tissues and spread to other parts of the body.

Prophase

Chromosomes condense and become visible; spindle fibers begin forming.

Prometaphase:

Nuclear envelope breaks down; spindle fibers attach to chromosomes at their kinetochores.

Metaphase

Chromosomes line up in the middle of the cell.

Anaphase

Sister chromatids separate and are pulled to opposite ends of the cell.

Telophase

New nuclear envelopes form around each set of chromosomes; chromosomes begin to uncoil.