Slide shows combined and modified from: AP BIOLOGY Chapter 6 What You Should Know Already from BIO I

CELL MEMBRANE (also called plasma membrane) PHOSPHOLIPID BILAYER with PROTEINS Hydrophobic tails face in Hydrophilic heads face out Outside of cell Inside of cell (cytoplasm) Cell membrane Proteins Protein channel Lipid bilayer Carbohydrate chains Membrane Image from: © Pearson Education Inc, Publishing as Pearson Prentice Hall; All rights reserved Phospholipid image from: SEE HOW MEMBRANES FORM

FLUID MOSAIC MODEL Molecules in cell membranes are constantly moving and changing Click here to See Fluidity Animation from:

CELL MEMBRANES act as boundary selectively permeable ~ gases & hydrophobic molecules can pass through ~ large, ionic, OR polar molecules need help (facilitated diffusion, ion channels, Na+-K+ pump, endocytosis & exocytosis)

CYTOPLASM (Between nucleus and cell membrane) Includes ORGANELLES- small structures with a specific function CYTOSOL-semi-fluid “goo” Image from: Image from:

NUCLEUS Surrounded by DOUBLE membrane (Nuclear envelope) Nuclear pores- allow molecules in & out Contains DNA Control center Replication (DNA → DNA) Transcription (DNA → RNA) Image from:

NUCLEOLUS Dark spot in nucleus Produces ribosomal RNA Assembles ribosomes (RNA & proteins) Image from:

DNA CHROMATIN- spread out in NON-dividing cells to access info CHROMOSOMES- condensed in dividing cells for easier transport

Cytoskeleton Network of protein fibers supporting cell shape and anchoring organelles – Microtubules – Microfilaments

RIBOSOMES Composed of two subunits that join and attach to messenger RNA Made of r-RNA & proteins Site of protein synthesis (~translation)

ENDOPLASMIC RETICULUM (ER) Lipid bilayer continuous with nuclear envelope Smooth ER no ribosomes synthesis of lipids metabolism of carbohydrates stores calcium detoxification of drugs and poisons Rough ER with ribosomes synthesis of secretory proteins (glycoproteins) membrane production Image from:

Golgi apparatus ( collection of Golgi bodies) “UPS” of cell Modify, sort, & package molecules from ER for storage OR transport out of cell Image from: Image from:

Animation from: See a Golgi movie

EVERYTHING’S CONNNECTED!

Lysosomes - membrane-bound vesicles containing digestive enzymes Breaks down food unwanted cell parts bacteria helps in APOPTOSIS “programmed cell death” See lysosomes in actionin action:

“PROGRAMMED CELL DEATH” APOPTOSIS Embryo development Cell maintenance Signal to self destruct lost in cancer cells

CENTRIOLES Made of microtubules Appear during cell division in animal cells to pull chromosomes apart

CENTRIOLES/MITOTIC SPINDLE Made of MICROTUBULES (Tubulin) Image from:

MITOCHONDRIA DOUBLE MEMBRANE (inner membrane = cristae) Has own DNA Powerplant of cell ~ site of cellular respiration ~ burn glucose ~ store energy as ATP Images from:

CHLOROPLASTS DOUBLE MEMBRANE Has own DNA Contains thylakoid sacs with chlorophyll for photosynthesis

Move substances past cells Help move cells FLAGELLA & CILIA Made of microtubules arrangement

CILIA Many short FLAGELLA Few Long WHAT’S THE DIFFERENCE? Animation from:

WHAT’S SPECIAL ABOUT PLANT CELLS? Cell wall HUGE vacuoles Chloroplasts No centrioles

CELL WALL Outside cell membrane Supports and protects cell Plants- Cellulose makes it “sturdy” Bacteria- have peptidoglycan instead

VACUOLES Huge in plants Storage space for water, food, enzymes, waste Image from:

VACUOLES can store WATER

Freshwater organisms have contractile vacuoles to control excess water in cells (HOMEOSTASIS)

WHAT’S DIFFERENT ABOUT BACTERIAL CELLS? Cell wall NO NUCLEAR MEMBRANE DNA is circular No membrane bound organelles

WHICH IS BIGGER? _________ > _____________ > ___________ Plant cellAnimal cell bacteria

DIFFERENCES IN ANIMAL CELLS, PLANT CELLS, AND BACTERIA ANIMAL CELLPLANT CELLBACTERIA Eukaryotes Prokaryotes Cell membrane Nuclear membrane NO nuclear membrane NO cell wallCell wall made of CELLULOSE Cell wall made of PEPTIDOGLYCAN Has ribosomes DNA in multiple chromosomes DNA is a single circular ring CYTOSKELETON Small vacuolesReally big vacuoleNO vacuoles Has lysosomesFew lysosomesNO lysosomes Has centriolesNO centrioles NO chloroplastsChloroplastsNO chloroplasts SMALLER sizeSMALL sizeSMALLEST size

Slide shows combined and modified from: AP BIOLOGY Chapter 6 Cell Structure & Function WHAT’S NEW you didn’t learn in BIO I?

NUCLEAR ENVELOPE DOUBLE MEMBRANE is fused in spots forming NUCLEAR PORES NUCLEAR LAMINA- netlike array of protein filaments on nuclear side of envelope that maintains the shape of the nucleus (Play a role in reforming nuclear membrane after cell division, if you inject antibodies to lamina proteins, nucleus can’t reform after mitosis)

NUCLEAR ENVELOPE Figure 6.10 Nucleus Nucleolus Chromatin Nuclear envelope: Inner membrane Outer membrane Nuclear pore Rough ER Pore complex Surface of nuclear envelope. Pore complexes (TEM). Nuclear lamina (TEM). Close-up of nuclear envelope Ribosome 1 µm 0.25 µm

ENDOMEMBRANE SYSTEM Regulates protein traffic and performs metabolic functions in the cell Includes: Plasma membrane Nuclear membrane Endoplasmic reticulum Golgi apparatus Vacuoles Lysosomes

INSULIN being released by pancreas cells using exocytosis

Golgi apparatus Cisternae = Flattened membrane sacs (look like stacked pancakes) 2 sides = 2 functions  cis = (receives vesicles by fusion)  trans = buds off vesicles to send to other places (shipping face)

Animation from: See a Golgi movie

EVERYTHING’S CONNNECTED!

LYSOSOMES (common in animal cells but rare in plant cells) Contain hydrolytic enzymes for intracellular digestion Food (Phagocytosis) Damaged organelles AUTOPHAGY ~ “eating self” See movie

LYSOSOMES: Uncontrolled release of lysosome contents into the cytoplasm can also cause cell death (necrosis) APOPTOSIS (self-destruct mechanism) “cell suicide” Embryonic development Removes damaged cells Immune response Cancer cells and AIDS virus override self-destruct signals

WHITE BLOOD CELLS USE LYSOSOMES TO DIGEST ENGULFED BACTERIA (Phagocytosis)

ANIMAL VACUOLES & VESICLES “transport vehicles” FOOD VACUOLES Phagocytosis/ fuse with lysosomes CONTRACTILE VACUOLES Freshwater organisms pump out excess water

PLANT VACUOLES (Central Vacuole) Surrounded by membrane = TONOPLAST Selectively permeable – controls what goes in & out STORAGE Water Stockpile proteins/inorganic ions Deposit metabolic byproducts Store pigments Store defensive compounds against herbivores

Other cell parts with membranes that are NOT part of the Endomembrane system: – Mitochondria – Plastids – Peroxisomes

MITOCHONDRIA- DOUBLE MEMBRANE Outer membrane Inner membrane (CRISTAE) increases surface area for chemical reactions Intermembrane space= Space between inner membrane & outer membrane MATRIX = Space inside cristae folds contains DNA, enzymes, ribosomes

Chloroplasts – site for photosynthesis in plants DOUBLE MEMBRANE Has own DNA Thylakoids – membrane sacs containing light-capturing pigments Grana – closed compartments of stacked thylakoid membranes Stroma – fluid surrounding thylakoids

PLASTIDS CHLOROPLASTS- contain pigment chlorophyll for photosynthesis CHROMOPLASTS- contain pigments that give fruits and flowers colors AMYLOPLASTS- store starch (amylose) in roots and tubers (colorless)

Who else has a circular chromosome not found within a nucleus?

Endosymbiotic Theory Originally proposed in early 1900’s Idea reintroduced in 1963 by Lynn Margulis Suggests that engulfed prokaryotes shared symbiotic relationship with host cell Advantages for both: ~ one supplies energy ~ other raw materials & protection

ENDOSYMBIOTIC THEORY See a movie about ENDOSYMBIOTIC THEORY

Evidence for Endosymbiotic theory 1. Mitochondria and chloroplasts have circular DNA like bacteria. 2. Mitochondria and chloroplasts have ribosomes whose size and structure resemble bacterial ribosomes. 3. Mitochondria and chloroplasts replicate independently of cell division using binary fission like bacteria. 4. Inner membranes of mitochondria and chloroplasts have a composition similar to bacterial membranes.

PEROXISOMES Other digestive enzyme sacs in both plants and animals NOT part of endomembrane system (proteins come from cytosol) In fat storing seeds (called GLYOXYSOMES) Break down fatty acids → sugars transport to mitochondria for energy In LIVER CELLS Help detoxify alcohol & other poisons PRODUCE HYDROGEN PEROXIDE (also a TOXIN) but have enzyme (CATALASE) to break this down H 2 O 2 → H 2 O + O 2