Concepts and Connections - Chapter 4 Vocabs

Bacterial Chromosomes

DNA in a bacterial cell

Capsule

The protein shell that encloses a viral genome

Cell wall

A protein layer external to the plasma membrane in plant cells, bacteria, fungus, and some protists; protects the cell and helps maintain its shape.

central vacuole

In a plant cell, a large membranous sac with diverse roles in growth and the storage of chemicals and waste.

centriole

A structure in an animal cell composed of cylinders of microtubule triplets arranged in a 9+0 pattern. An animal usually has a centrosome with a pair of centrioles involved in cell division.

chloroplst

An organelle found in plants and photosynthetic protists that absorbs sunlight and uses it to drive the synthesis of organic molecules (sugars) from carbon dioxide and water.

chromatin

The combination of DNA and proteins that constitutes eukaryotic chromosomes; often used to refer to the diffuse, very extended from taken by chromosomes when a cell is not dividing.

cytoskeleton

A network of protein fibers in the cytoplasm of a eukaryotic cell; includes microfilaments, intermediate filaments, and microtubules.

fimbriae

One of the short, hairlike projections on some eukaryotic cells that help attach the cells to their substrate or to other cells.

flagella

A long cellular appendage specialized for locomotion. The flagella of prokaryotes and eukaryotes differ in both structure and function. Like cilia, eukaryotic flagella have 9+2 arrangement of microtubules covered by the cell’s plasma membrane.

Golgi apparatus

An organelle in eukaryotic cells consisting of stacks of membranous sacs that modify, store, and ship products of the endoplasmic reticulum.

intermediate filament

An intermediate-sized protein fiber that is one of the three main kinds of fibers making up the cytoskeleton of eukaryotic cells. Intermediate filaments are ropelike, made of fibrous proteins.

lysosome

A digestive organelle in eukaryotic cells; contains hydrolytic enzymes that digest engulfed food or damaged organelles.

microfilament

The thinnest of the three main kinds of protein fibers making up the cytoskeleton of a eukaryotic cell; a solid, helical rod composed of the globular protein actin.

microtubule

The thickest of the three main kinds of fibers making up the cytoskeleton of a eukaryotic cell; a hollow tube made of globular proteins called tubulins; found in cilia and flagella.

mitochondria

An organelle in eukaryotic cells where cellular respiration occurs. Enclosed by two membranes, it is where most of the cell’s ATP is made.

nuclear envelope

A double membrane that encloses the nucleus, perforated with pores that regulate tragic with the cytoplasm.

nucleoid

A dense region of DNA in a prokaryotic cell

nucleolus

A structure within the nucleolus where ribosomal RNA is made and assembled with proteins imported from the cytoplasm to make ribosomal subunits.

nucleus

The genetic control center of a eukaryotic cell

perioxisome

An organelle containing enzymes that transfer hydrogen atoms from various substrates to oxygen, producing and then degrading hydrogen peroxide.

plasma membrane

The membrane at the boundary of every cell that acts as aselective barrier to the passage of ions and molecules into and out of the cell; consists of a phospholipid bilayer with embedded proteins.

plasmodesma

An open channel in a plant cell wall through which strands of cytoplasm connect from adjacent cells.

ribosome

A cell structure consisting of RNA and protein organized into two subunits and functioning as the site of protein synthesis in the cytoplasm. In eukaryotic cells, the ribosomal subunits are constructed in the nucleolus.

rough ER

That portion of the endoplasmic reticulum with ribosomes attached that make membrane proteins and secretory proteins.

smooth ER

The portion of the endoplasmic reticulum that lacks ribosomes.