CHAPTER 7 -2

Eukaryotic Cell Structure

Basic Cell Info

Cells are like factories Every part inside the cell has a specific job

Each part of a cell functions like a little organ Little organ = Organelle

Cells are divided into 2 parts Nucleus Cytoplasm

Cytoplasm is the jelly-like interior PLUS all the organelles outside the nucleus

Eukaryotic Cell Organelles

Plant and Animal: Cell membrane Nucleus Nucleolus Nuclear envelope Ribosomes Rough Endoplasmic Reticulum Smooth Endoplasmic

Reticulum Golgi Bodies (Apparatus) Lysosomes Mitochondria Vacuoles

Cytoskeleton

Animal Cells: Centrioles Many small vacuoles

Plant Cells: Cell walls Chloroplasts One central water Vacuole

Eukaryotic Animal Cell

Eukaryotic Plant Cell

Nucleus

Nucleus: control center of the cell

• houses chromatin • DNA bound to Proteins• Code for proteins and

molecules) Nuclear Envelope: a porous

membrane that surrounds the nucleus• Protects DNA from damage• Allows only specific

molecules in or out Nucleolus : A special, dense

location inside the nucleus• Site of ribosome formation

Ribosomes

Protein MachinesMade of ribosomal RNA

(rRNA) and proteinFound free floating and

attached to Rough Endoplasmic Reticulum

Attaches amino acids (Protein monomers) together into a chain (polypeptide) Uses messenger RNA

(mRNA) and transfer RNA (tRNA)

Rough Endoplasmic Reticulum

An extensive network of membrane-bound tubules surrounding the nucleus

Shapes proteins as they are being formed by ribosomes The attached ribosomes

“feed” the forming protein into the RER through pores

Called “Rough” ER because of the rough appearance ribosomes give it under a microscope

Smooth Endoplasmic Reticulum

An extension of RERDoes NOT have

ribosomes covering itHelps make fats

(lipids) and cholesterols This is where

components of the cell membrane are initially formed as well as membranes for other organelles

Golgi Bodies (Apparatus)

Look like stacks of flattened pancakes

Made of pinched-off pieces of RER containing folded/shaped proteins

Packaging/Shipping department of cell Similar to a post office,

this organelle sends the proteins to their final destination (either cell membrane or out of the cell)

Lysosomes

Janitors of the cellContain lots of

enzymes and have a pH of about 5 (acidic)

Break down old organelles and metabolic wastes before they harm the cell

Vacuoles

Storage Closets of cell Store food, water, waste Plant cells have one large,

central water vacuole Allows the plant to support

heavy structures such as leaves Animal cells can have many

small vacuoles for food and water

Some single-celled organisms have special vacuoles called contractile vacuoles These pump out excess water

by contracting in order to maintain homeostasis

Plant Cell: Central Vacuole

Mitochondria

Powerhouse of the cellDouble-membrane

organelleCreates energy in the form

of adenosine triphosphate (ATP)

Site of Aerobic Respiration! In other words, this is where

sugar is broken down with oxygen to make energy (ATP)

Cells that need LOTS of energy have LOTS of mitochondria EX: muscle cells, brain cells

Has its own DNA

Plant Cell Exclusive: Chloroplast

Double-membrane organelles

Site of photosynthesis

Contain the green pigment chlorophyll (a protein)

Builds sugar (glucose) molecules from Water, Co2, in the presence of sunlight

Has its own DNA

Cytoskeleton

Internal network of protein filaments and tubules

Provide: Shape and support Pathways for molecules

and organelles to move Ex: Golgi bodies send

proteins out along microtubules

Movement of cell parts Ex: cilia, microvilli,

flagella

Animal Cell Exclusive: Centrioles

Aide in cell divisionMade of

microtubulesForm spindle fibers

and astral rays during mitosis and meiosis (More to come in

chapters 10 and 11)

Cell Membrane

The bouncerDecides what goes in

and out of the cellControls cellular

transport based on molecule size AND special transport proteins that are specific for moving certain molecules across the membrane

Made MOSTLY of lipids, contains SOME proteins

Plant Cell Exclusive: Cell Wall

Give the plant cell rigidity and support

Made of cellulose Plant starch

Prevents the plant cell from exploding when water pressure (osmotic pressure) is too high in the cell

Important Points!

Plant and animal cells are Eukaryotic!Prokaryotic cells contain SOME but not all

of the structures reviewed in this power point

Bacteria (Prokaryotes) have NO nucleus, but they MIGHT have a cell wall

Fungi (Eukaryotes) have NO chloroplast, but do have a nucleus and cell wall Fungi are NOT plants!