Chapter 2: Cells" The Living Units"

What is the organization of a living organism?

atom, molecule, macromolecule, organelle, cell, tissue, organ, organ system, and organism

What are cells (five points)

1. Smallest living units in the body

2. Perform all functions necessary to sustain life

3. Obtain nutrients from the surrounding body fluids

4. Disposes of its wastes and maintains its shape and integrity

5. Produced by the division of preexisting cells, they can replicate themselves

Function of Cells due to

organelles, enzymes, and metabolism

Function of an organelle

“Little organs” carry on essential functions of cells”

Function of an Enzyme

direct chemical reactions in cells

What is metabolism?

the sum of all chemical reactions in the cell

What are the three main components of a cell

Plasma membrane, cytoplasm, and nucleus

What is a Plasma Membrane?

1. It is the wall of the cell

2. Determines which substances enter or leave the cell

What are the types of membrane proteins?

Integral proteins and Peripheral proteins

What is an integral protein

firmly imbedded in, or attached to lipid bilayer

what is a transmembrane protein?

it is a type of integral protein that span across the entire membrane

What is a peripheral protein?

attach to membrane surface

What is the function of the Plasma Membrane? (four points)

1. Physical isolation

2. Regulation of exchange with the environment

3. sensitivity

4. structural support

What is Osmosis

a diffusion of water across a membrane (movement of water)

Simple Diffusion

molecules move from a region where they are more concentrated to an area where they are less concentrated → uncharged and fat-soluble molecules (high to low)

Facilitated Diffusion

molecules move from a region where they are more concentrated to an area where they are less concentrated → charged and water-soluble molecules (high to low)

Active Diffusion

molecules move from a region where they are less concentrated to an area where they are more concentrated → required energy

What is endocytosis?

mechanism by which particles enter cells

What are the three types of endocytosis’

1. Phagocytosis: “cell eating”

2. Pinocytosis: “cell drinking”

3. Receptor-mediated endocytosis: “receptors get activated when something binds with it”

What is Exocytosis?

Mechanism that moves substances out of the cell

Cytoplasm (location and function)

Location: lies internal to plasma

Function: stored nutrients, secretory products, and pigment granules

What is Cytosol

It is a jelly-like fluid in which other cellular elements are suspended and consists of water, ions, and enzymes

Ribosomes

part of the cell that makes proteins by reading instructions from RNA.

Rough Endoplasmic reticulum

ribosomes stud the external surfaces

Smooth Endoplasmic reticulum

consists of tubules in a branching network

Golgi apparatus

sorts products of rough ER and sends them to proper destination

Mitochondria

generate most of the cell’s energy; most complex organelle

Lysosomes

digest external invaders and waste

Peroxisomes

break down internal toxins and fats

Cytoskeleton

“cell skeleton” = an elaborate network of rods

What are the three different rods in a Cytoskeleton?

1. Microtubules: cylindrical structures made of proteins

2. Microfilaments: filaments of contractile protein actin

3. Intermediate filaments: protein fibers

Microtubule

originate from centrosome

Microfilament

found internal to the plasma membrane of the cell

Intermediate Filament

most stable and permanent

Centrosome

composed of centrosome matrix and centrioles

Centrioles

act in forming cilia, flagella, and mitotic spindle fibers

Nucleus

control center of cell, DNA directs the cell’s activities, and nucleus is approximate 5um in diameter

Nuclear envelope

Nuclear pore allows large molecules (RNA) to be exported from the nucleus or proteins from the cytoplasm to come in

nucleolus

contains parts of several chromosomes and site of ribosome subunit manufacture

Chromosomes

highest level of organization of chromatin

Chromatin

compsed of DNA and histone proteins