Biology Chapter 4 Cell Structure

Cell Theory

1. All organisms are composed of one or more cells 2. Cells are the smallest living things, the basic units of organization 3. Cells arise only by division of a previously existing cell.

Chromatin

A complex structure made up of organized DNA and proteins called histones

thylakoid

A flattened membrane sac inside the chloroplast, used to convert light energy into chemical energy.

Actin

A globular protein that links into chains, two of which twist helically about each other, forming microfilaments in muscle and other contractile elements in cells.

tonoplast

A membrane that encloses the central vacuole in a plant cell, separating the cytosol from the vacuolar contents, called cell sap; also known as the vacuolar membrane.

Peroxisome

A microbody containing enzymes that transfer hydrogen from various substrates to oxygen, producing and then degrading hydrogen peroxide.

kinesin

A motor protein that uses the chemical energy of ATP to transport vesicles, particles, or chromosomes along microtubules.

Plasma Membrane

A phospholipid bilayer that enclose a cell and separates its contents from its surroundings.

endosymbiosis

A process in which a unicellular organism (the "host") engulfs another cell, which lives within the host cell and ultimately becomes an organelle in the host cell; also refers to the hypothesis that mitochondria and plastids were formerly small prokaryotes that began living within larger cells.

myosin

A protein present in muscle fibers that aids in contraction and makes up the majority of muscle fiber

Integrin

A receptor protein built into the plasma membrane that interconnects the extracellular matrix and the cytoskeleton.

cilia

A short cellular appendage specialized for locomotion, formed from a core of nine outer doublet microtubules and two inner single microtubules ensheathed in an extension of plasma membrane.

dynein

A special motor protein that moves along the microtubule toward the negative end; responsible for rentrograde axoplasmic transport

grana

A stacked portion of the thylakoid membrane in the chloroplast. Grana function in the light reactions of photosynthesis

Secondary Wall

A strong and durable matrix often deposited in several laminated layers for plant cell protection and support.

basal body

A structure resembling a centriole that produces a cilium or flagellum and anchors this structure within the plasma membrane.

Middle Lamella

A thin layer of adhesive extracellular material, primarily pectins, found between the primary walls of adjacent young plant cells.

Nuclear Pores

Allows small molecules to diffuse freely between nucleoplasm and cytoplasm while controlling the passage of proteins and RNA-protein complexes.

Cytoskeleten

An internal protein scaffold that supports all eukaryotic cells

Gram-negative

Bacteria that have a complex, multilayered cell wall that does not retain purple dye.

Gram-positive

Bacteria that have a thick, single-layered peptidoglycan cell wall that retains a violet dye

Ribosome

Carry out protein synthesis.

Nucleosome

DNA wrapped around histones.

Central Vacuole

In plants. A large membrane bounded sac, which stores proteins, pigments and waste materials.

cristae

Infoldings of the inner membrane of a mitochondrion that houses the electron transport chain and the enzyme catalyzing the synthesis of ATP.

Microtubule-organizing centers

Its the site where Microtubules originate and act as the anchor for finished fiber

Flagella

Long threadlike structures protruding from the surface of a cell that are used in locomotion.

Compound microscope

Magnifies in stages using several lenses

microbodies

Membrane-bound organelles specialized as containers for metabolic reactions. (Peroxisomes and Glyoxysomes)

Resolution

Minimum distance two points can be apart and still be distinguished as two separated points.

Centrioles

One of two tiny structures located in the cytoplasm of animal cells near the nuclear envelope; play a role in cell division.

Light microscope

Operates with visible light, uses two magnifying lenses

Nucleolus

Region in the nucleus where intensive synthesis of ribosomal RNA is taking place.

Vesicles

Small membrane bounded sacs that store and transport materials

Rough ER

That portion of the endoplasmic reticulum studded with ribosomes.

Smooth ER

That portion of the endoplasmic reticulum that is free of ribosomes.

9+2 structure

The cili and flagella are each composed of 9 pairs of microtubules located around its circumference and one pair of microtubules running down its center

plastid

The collective of a family of closely related plant organelles, including chloroplasts, chromoplasts, and amyloplasts (leucoplasts).

Primary wall

The first thin, pliable wall of young plant cells

Extracellular Matrix

The matrix of glycoproteins that animal cells deposit outside the plasma membrane which provide support, strength, and resilience

Cytosol

The part of the cytoplasm that contains organic molecules and ions in solution

Cell Wall

The rigid, outermost layer of the plants, some protisits, and most bacteria; the cell wall surrounds the plasma membrane

Cytoplasm

The semifluid matrix that fills the interior of a cell.

Nuclear envelope

Two phospholipid bilayer membranes that binds the surface of the nucleus

amyloplast

Unpigmented plasids (lucoplast) that store starch grains, abundent in cells of stems, tubers, and seeds

Electron microscope

Uses electron beams rather than light, because electron beams have a shorter wavelength

Fibronectin

a glycoprotein that helps animal cells attach to the extracellular matrix.

Endoplasmic Reticulum

a system of membranes that is found in a cell's cytoplasm and that assists in the production, processing, and transport of proteins and in the production of lipids

Nucleoid

an area near the middle of a prokaryotic cell that houses the cell's DNA

vacuole

cell organelle that stores materials such as water, salts, proteins, and carbohydrates

Mitochondria

eukaryotic membrane-bound organelles that transform energy stored in food molecules; has a highly folded inner membrane that produces energy-storing molecules

Cisternae

flattened membrane sacs that make up the golgi apparatus

Golgi Bodies

flattened sacs and tubes that receive proteins and other newly formed materials from the endoplasmic reticulum, packages them and distributes them to other parts of the cell

Microtubules

hollow tubes of protein about 25 nanometers in diameter, support the cell and moves organelles within the cell

cisternal space

internal compartment of the ER

matrix

lies inside the inner membrane of mitochondria.

Pericentriolar Material

material surrounding centrioles of the centrosome that seem to be responsible for nucleating microtubules; contains gamma tubulin which is a protein component that interacts with cytoplasmic tubulin

lysosome

membrane-bound sac containing digestive enzymes that can break down proteins, nucleic acids, and polysaccharides

mRNA

messenger RNA; type of RNA that carries instructions from DNA in the nucleus to the ribosome

Chloroplast

organelle found in cells of plants and some other organisms that captures the energy from sunlight and converts it into chemical energy

glycoproteins

proteins that have carbohydrates covalently bonded to them

Intermediate filaments

range from 7-11nm in diameter, and strengthen the cell and help maintain its shape, stabilize the positions of organelles, and stabilize the position of the cell with respect to surrounding cells through specialized attachment to the cell membrane

rRNA

ribosomal RNA; type of RNA that makes up part of the ribosome

Prokaryotes

simple organisms lacking a nucleus and internal membrane systems

Glyoxysome

specialized type of plant peroxisome that contains enzymes responsible for the conversion of stored fat to carbohydrate in germinating seeds.

golgi apparatus

stack of membranes in the cell that modifies, sorts, and packages proteins from the endoplasmic reticulum

intermembrane space

the region between the inner membrane and the outer membrane of a mitochondrion or a chloroplast. The main function of the intermembrane space is nucleotide phosphorylation.

Nucleus

the repository of the genetic information that leads to the synthesis of nearly all proteins of a living cell.

Actin Filaments

thinnest filaments (7nm); composed of 2 strands of actin monomers that spiral around each other; have plus and minus end; play key role in cell strength and shape; concentrated near plasma membrane for support

tRNA

transfer RNA; type of RNA that carries amino acids to the ribosome