Cell Biology and Molecular Genetics Review

Vocabulary flashcards covering cell structure, membrane transport, cell division, protein synthesis, and DNA replication based on lecture notes.

Nucleus

The cell's control center that contains DNA.

Multinucleate

Possessing many nuclei, as found in muscle cells and some liver cells.

Anucleate

Lacking a nucleus, as seen in mature RBC (red blood cells).

Nuclear envelope

A double membrane barrier that surrounds the nucleus, has an outer part continuous with the rough ER, and contains nuclear pores that control entry and exit of molecules.

Nucleoli

Dark staining bodies inside the nucleus where ribosomes are made.

Chromatin

The combination of DNA plus protein found in the nucleus.

Histones

Proteins that allow for the compact and orderly packing of long DNA molecules.

Phospholipids

Membrane lipids composed of a polar hydrophilic (water loving) head and a nonpolar hydrophobic (water fearing) tail.

Cholesterol

A lipid constituting 20% of membrane lipids that stabilizes the membrane.

Glycolipids

Lipids with attached sugars that make up 5% of membrane lipids and function in cell recognition.

Glycoprotein

A structure consisting of a protein with attached sugar that functions in specific biological cell recognition and chemical reactions.

Tight junctions

Impermeable junctions that bind cells together into leak proof sheets.

Desmosomes

Anchoring junctions that prevent cells from being pulled apart as a result of mechanical stress.

Gap junctions

Junctions that allow communication between cells by allowing molecules to travel directly from one cell to the next through channels.

Cytosol

The fluid portion of the cytoplasm containing water, protein, salt, and sugars.

Interstitial fluid

The fluid outside cells that is a rich nutrient soup containing amino acids, sugars, fatty acids, vitamins, hormones, salts, and wastes.

Passive transport

Transport across the plasma membrane that requires no energy ($\text{ATP}$) and moves molecules down their concentration gradient from high to low concentration.

Simple diffusion

The unassisted movement of small, nonpolar, lipid soluble substances directly through the lipid bilayer.

Facilitated diffusion

Transport across a membrane assisted by carrier or channel proteins.

Channel proteins

Water filled transport proteins that allow substances such as ions to pass through the membrane.

Carrier proteins

Transport proteins that bind to a molecule, change shape, ferry it across the membrane, and exhibit a saturation limit (example: glucose transporter).

Osmosis

The diffusion of $H_2O$ across a membrane through aquaporin channel proteins.

Aquaporins

Channel proteins specifically designated for the diffusion of $H_2O$.

Filtration

Passive transport where water and solutes are forced through a membrane by fluid hydrostatic pressure from a high pressure area to a lower pressure area (such as in kidney capillaries to form urine).

Primary active transport

Transport that directly uses $\text{ATP}$ to move molecules against their concentration gradient from low to high concentration (examples: $Ca^{2+}$ pump, $H^+$ pump, sodium pump).

Secondary active transport

Transport that moves more than one substance at a time across the membrane using gradients created by active transport.

Symport

A secondary active transport mechanism where two substances are moved across the membrane in the same direction.

Antiport

A secondary active transport mechanism where two substances cross the membrane in opposite directions.

Exocytosis

Vesicular transport that ejects substances out of the cell.

Endocytosis

Vesicular transport where the cell ingests substances within the cell.

Phagocytosis

A type of endocytosis known as 'cell eating' that engulfs large and solid material.

Pinocytosis

A type of endocytosis that takes in fluid containing dissolved molecules (such as in intestinal cells).

Receptor-mediated endocytosis

A process that concentrates specific substances (ligands like insulin, iron, and cholesterol) that bind to receptor proteins.

Gene

A segment of DNA that codes for one polypeptide.

Exon

The part of DNA that codes for polypeptides.

Transcription

The process occurring in the nucleus where RNA is formed from DNA.

Translation

The process of protein synthesis occurring in the cytoplasm by ribosomes where polypeptides are formed from RNA.

Primase

Enzyme in DNA replication that places primers to signal when replication starts.

Helicase

Enzyme in DNA replication that unzips the DNA codes.

Ligase

Enzyme in DNA replication that connects the Ozaukee fragments.

DNA polymerase

Enzyme that builds new DNA strands during replication.