CELL BIOLOGY CELL STRUCTURE FUNCTION Chapter 4 CELL

CELL BIOLOGY

CELL STRUCTURE & FUNCTION Chapter 4

CELL (Plasma) MEMBRANE • Holds contents inside

CELL MEMBRANE • Controls what enters and leaves cell

FLUID MOSAIC MODEL Image from: http: //bio. winona. msus. edu/berg/ILLUST/memb-mod. jpg

CELL MEMBRANES are mainly PHOSPHOLIPIDS POLAR HEAD“hydrophillic” 2 NON-POLAR TAILS“hydrophobic”

WATER INSIDE CELL Water WATER OUTSIDE CELL

Cell membranes form because the hydrophobic tails are trying to stay away from water!

CELL MEMBRANE BILAYER Made of PHOSPHOLIPIDS & PROTEINS

MEMBRANE PROTEINS Image modified from: http: //bio. winona. msus. edu/berg/ILLUST/Bil&mem 3. jpg PERIPHERAL ________ stick only on the SURFACE of the membrane Can be on inside or outside of cell

MEMBRANE PROTEINS INTEGRAL _______ proteins that stick into the membrane Can go part way OR all the way through Image modified from: http: //bio. winona. msus. edu/berg/ILLUST/Bil&mem 3. jpg

OTHER MOLECULES in MEMBRANES GLYCOPROTEINS ___________ Proteins with carbohydrates attached Function in cell recognition Organ donors Foreign invader ID

OTHER MOLECULES in MEMBRANES STEROIDS ___________ Lipids made with carbon rings STRUCTURAL Fit between hydrophobic tails of phospholipids

SELECTIVELY PERMEABLE “Semi-permeable” Let’s some kinds of molecules pass through, but keeps others OUT!

Passive Transport • Moves from an area of greater concentration. to and area of lesser concentration • Move “down a concentration gradient”

Passive Transport - Osmosis • Moves water from area where it is most pure to area where it is less pure • Hypotonic • Hypertonic • Isotonic (Equilibrium)

Osmosis • Hypertonic = less pure (more solute) • Hypotonic = more pure (less solute) • Isotonic = equal

Passive Transport – Ion Channels • Integral proteins form channels that allow substances to pass through

Passive Transport – Facilitative Diffusion • Proteins “carry” substances across the cell membrane

Active transport - endocytosis • Movement of large substances into the cell

Active Transport - exocytosis • Large particles leave the cell

CYTOPLASM = cytosol + organelles CYTOSOL ________ Fluid portion of the cytoplasm ORGANELLES _________ small structures with a special function

CYTOSKELETON = the support system of the cell A. Microtubules B. microfilaments

NUCLEUS = the “control center” of the cell

NUCLEUS A. Contains genetic material

CHROMATIN (DNA & proteins) Thin form of DNA

CHROMOSOMES (DNA & proteins) Thick form of DNA

NUCLEUS B. Surrounded by a nuclear envelope 1. contains pores for materials to enter and leave the nucleus

NUCLEUS C. Contains the nucleolus = area of densely-packed DNA 1. makes ribosomes

MITOCHONDRIA = the “powerhouse” of the cell A. Converts glucose into ATP 1. occurs during the process of respiration

MITOCHONDRIA 2. Reaction occurs on the inner membrane of the mitochondria known as the cristae Increases surface area for more chemical reactions to happen

MITOCHONDRIA B. Contains its own DNA = mt. DNA 1. mother is only person to pass mt. DNA to offspring

-used to identify bodies Jesse James

Ribososmes = make proteins(attach amino acids into long chains) A. Some ribosomes are found floating in the cytoplasm - make proteins for inside the cell B. Some ribosomes are found attached to endoplasmic reticulum - make proteins for outside of cell

ROUGH ENDOPLASMIC RETICULUM (ER) = carries proteins through the cell (highway system)

ROUGH ENDOPLASMIC RETICULUM (ER) A. Has ribosomes attached

SMOOTH ENDOPLASMIC RETICULUM (ER) = detoxifies the cell A. Has no ribosomes attached

CENTRIOLES = • Appear during cell division to pull chromosomes apart

CENTRIOLES

GOLGI BODY (APPARATUS) = • “Packaging centers” of the cell • Packages molecules for transport out of cell. Puts proteins into vesicles.

All the cell membranes interconnect

It’s ALL connected!

VACUOLES • Storage for enzymes and waste

LYSOSOMES = Contain enzymes use to help break down food or break down tissues

Peroxisomes = bags of enzymes used to help break down chemicals A. Used to break down hydrogen peroxide in cells

Cilia/Flagella= move the cell or move substances past the cell • Many • short * one or two * long

How are Bacteria and Plant Cells Different from Animal Cells?

WHICH IS BIGGER? Plant cell Small Animal Cell Bacteria Smaller Smallest

2 KINDS OF CELLS _________ PROKARYOTES “No nucleus or membrane bound organelles” They have a cell membrane around outside. No membranes around their DNA NO organelles surrounded by membranes inside EXAMPLE: Bacteria

BACTERIA • No nuclear membrane • No membrane bound organelles • Cell wall • Single loop of DNA • Few organelles

2 KINDS OF CELLS EUKARYOTES _________ “Nucleus with membrane bound organelles” They have a cell membrane around outside. They have a nuclear membrane around their DNA and organelles surrounded by membranes inside EXAMPLE: Animal & plant cells

CELL WALL Supports and protects cell Outside of cell membrane Made of cellulose Different than bacteria cell wall

Plasmodesmata • Connect adjacent plant cells

Plasmodesmata

Vacuole • large • Water –filled • Provides support for the plant (turgor)

Chloroplasts • Green pigment • Most numerous

Chromoplast • Additional pigments (red, orange, yellow)

Leucoplasts • Store starch

PLANT CELLS • • Cell wall Plastids Bigger vacuoles No centrioles

2 KINDS OF ORGANISMS ___________ AUTOTROPHS Can make their own food Example: Green Plants _________

2 KINDS OF ORGANISMS HETEROTROPHS ___________ Can’t make their own food Get energy by eating other organisms Animals & YOU Examples: ________

ALL LIVING THINGS ARE MADE OF…. . CELLS ______

CELL WALL Supports and protects cell Outside of cell membrane Made of different molecules than plant cell wall

CHLOROPLASTS • Use energy from sun to make glucose for food

CHLOROPLASTS • Surrounded by DOUBLE membrane • Thylakoid stacks contain enzymes for photosynthesis • Contain own DNA

VACUOLES Storage for enzymes and waste Vacuoles are much larger in plants

NO CENTRIOLES in Plants