Organelles in Animal and Plant Cells
Jan 19, 2016
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