Organelles in Animal and Plant Cells

Basics of Cell Structure

Not all cells are alike! They vary in… A) size B) shape C) internal organization

SIZE: range from .2m – 0.2um (most are 10-50um)

-not all are microscopic (most are) ex: giraffe’s nerve cells extend 6.5 ft. down it’s leg!!

Cells are limited in size by the ratio between their outer surface area and their volume

Eukaryotic Cells

Large

Genetic material is ENCLOSED IN A NUCLEUS

Contain a variety of organelles – membrane-enclosed structures that perform specific functions within the cell

Cell Walls

Stiff coatings on outer surfaces of bacteria, plants, fungi, and some protists are cell walls

Support and protect fragile cells; usually porous

Cell walls are composed of polysaccharides like cellulose or chitin

Cell walls in plants may have multiple layers

Primary cell walls in plants are outermost

Secondary cell walls are innermost Cell walls of adjacent cells joined by

middle lamellae

Plasma MembraneDouble layer of

phospholipids Isolates cell contents

from external environment

Regulates flow of materials into and out of the cell

Interaction with other cells and extracellular environment (outside of cell)

Cytoplasm All material and structures that lie inside the plasma membrane, but outside nucleus

Cytosol: fluid potion; water, salts and organic molecules; site of biochemical reactions

Cytoskeleton

Protein fibers, give shape an organization to the cellMicrofilaments, intermediate filaments, and

microtubules3 functions:

1. Shape (intermediate filaments)

2. Cell/Organelle Movement (microfilaments and microtubules)

3. Cell Division (microfilaments and microtubules)

Cell Movement

Cilia (“eyelash”) - move cell through fluid/fluid past cell

Flagella (“whip”) - move cell through fluid

Structure:

• Ring of nine, one pair in the center

• Outer pairs of arms interact to cause movement

• Arise from basal body (just below plasma membrane)

• Use ATP to move

Centrioles and centrosome

• Produce the microtubules of cilia and flagella, and those that form the spindle during animal cell division

Nucleus

Membrane bound hold chromosomes

3 componentsNuclear membrane Chromatin Nucleolus

The Nucleus

The nuclear envelope separates chromosomes from cytoplasmEnvelope is a double membrane with nuclear pores for

transportOuter membrane is studded with ribosomes

The NucleusThe nucleus contains DNA in various configurations

Compacted chromosomes (during cell division)Diffuse chromatin (as DNA directs reactions through an

RNA intermediate by coding for proteins)

The NucleusDarker area within the nucleus called the nucleolus

Functions as the site of ribosome synthesisRibosomes synthesize proteinsFree Floating Ribosome: make proteins for the cellRibosomes attached to ER: make proteins to be exported

from the cell

Endoplasmic ReticulumEndoplasmic Reticulum: (ER)

acts as a highway for molecules to move around the cell.Smooth ER: does NOT contain

ribosomes; Contains enzymes that detoxify drugs (in liver cells) or synthesizes lipids

Rough ER: does contain ribosomes; Produces proteins and phospholipids destined for other membranes or for secretion (export)

Golgi Apparatus (Body)

A set of stacked flattened sacs product is assembled (moves from ER

to golgi, where it is put together and adjusted)

product is packaged (in new sacs) product is mailed out (sent out of cell)

Lysosome

Membrane enclosed vesicles

Contain digestive enzymes

Digest food particles by fuding with food vacuoles and digest food into basic nutrients

Vacuole

Fluid-filled sacs with a single membrane

Functions of vacuolesContractile vacuoles in freshwater

organisms used to collect and pump water outPlant central vacuoles used in several ways

Maintain water balanceStore hazardous wastes, nutrients, or

pigmentsProvide turgor pressure on cytoplasm to

keep cells rigid

MitochondriaExtract energy

from food molecules and store in high energy bonds of ATP• Energy extraction

process involves anaerobic and aerobic reactions

Plastids

a) chloroplasts : site for photosynthesis b) chromoplasts: stores red and yellow pigmentc) leucoplasts: non pigmented

ChloroplastsA type of plastid

Functions of plastids Storage for photosynthetic products like

starch Storage of pigment molecules giving

color to ripe fruit

Cell Wall

Cell Wall: rigid covering made of cellulose, protects cell, goes OUTSIDE cell membrane, porous enough for certain substances

Prokaryotes

Small

Surrounded by stiff cell wall

Surface features – capsules and slime layers

Single circular chromosome in central region called nucleoid; DO NOT CONTAIN A NUCLEUS

Ribosomes