Mid-Term Exam Review

Microscopes provide windows to the world of the cell The light microscope enables us to see the overall shape and structure of a cell

Electron microscopes~ can view ultrastructures of cells They use a beam of electrons instead of light The greater resolving power of electron microscopes

The Cell Theory Robert Hooke (1600’s/ English)) used a compound light microscope to study cork, the dead cells of oak bark. Cells are the basic building blocks of all living things. Schleiden & Schwann (1830;s, German) their observations & conclusions are summarized as the cell theory

The cell theory is made up of three main ideas: 1.All organisms are composed of one or more cells. 2. The cell is the basic unit of organization of organisms. 3. All cells come from preexisting cells.

Why study cells? Cells  Tissues  Organs  Bodies bodies are made up of cells cells do all the work of life!

The Jobs of Cells Cells have 3 main jobs make energy make proteins need energy for all activities need to clean up waste produced while making energy make proteins proteins do all the work in a cell, so we need lots of them make more cells for growth to replace damaged or diseased cells Our organelles do all these jobs!

2 Types of cells plant cells animal cells bacteria cells Prokaryote - no organelles Eukaryotes - organelles plant cells animal cells

Prokaryotic cells-Bacteria small, relatively simple cells They do not have a nucleus enclosed by a plasma membrane and is usually encased in a rigid cell wall Inside the cell are its DNA and other parts

Eukaryotic cells are partitioned into functional compartments All other life forms are made up of one or more eukaryotic cells These are larger and more complex than prokaryotic cells Eukaryotes are distinguished by the presence of a true nucleus The cytoplasm contains organelles Many organelles have membranes as boundaries These compartmentalize the interior of the cell This allows the cell to carry out a variety of activities simultaneously

Animal Cell

Plant Cell

Animal vs. Plant Cells What are the main differences? Animal ONLY has Extracellular matrix Flagellum or cilia Centrioles Cellular Junctions Gap junctions Tight Junctions Desmosomes

Animal vs. Plant Cells What are the main differences? Plant ONLY has Large Central Vacuole Chloroplasts Rigid Cell Wall Plasmodesmata

Prokaryotes vs. Eukaryotes Prokaryotes ONLY have? Nucleoid Pili – attachment structure Cell Wall with peptidoglycan

Prokaryotes vs. Eukaryotes Eukaryotes ONLY have? Membrane Bound Organelles Cytoskeleton Cellular Junctions Centrioles (No mitosis in prokaryotes)

Prokaryotes vs. Eukaryotes What is common to both? Chromosomes Ribosomes Cell membrane (Plasma membrane) Cytosol (Cytoplasm)

Cell sizes vary with their function Cell size and shape relate to function

Cell size comparison most bacteria eukaryotic cells Animal cell Bacterial cell Animal cell most bacteria 1-10 microns eukaryotic cells 10-100 microns micron = micrometer = 1/1,000,000 meter diameter of human hair = ~20 microns

Natural laws limit cell size a cell must be large enough to house the parts it needs to survive and reproduce The maximum size of a cell is limited by the amount of surface needed to obtain nutrients from the environment and dispose of wastes

A small cell has a greater ratio of surface area to volume than a large cell of the same shape Total surface area of 27 small cubes = 16,200 µm2 Surface area of one large cube = 5,400 µm2

Organelles Organelles do the work of cells each structure has a job to do keeps the cell alive; keeps you alive They’re like mini-organs! Model Animal Cell

1. Cells need power! Making energy to fuel daily life & growth, the cell must… take in food & digest it take in oxygen (O2) make ATP remove waste organelles that do this work… cell membrane lysosomes vacuoles & vesicles mitochondria ATP

Cell membrane Function Structure separates cell from outside phosphate “head” Function separates cell from outside controls what enters or leaves cell O2, CO2, food, H2O, nutrients, waste recognizes signals from other cells allows communication between cells Structure double layer of fat phospholipid bilayer receptor molecules proteins lipid “tail”

cytoplasm jelly-like material holding organelles in place cell membrane cell boundary controls movement of materials in & out recognizes signals

Vacuoles & vesicles Function Structure moving material around cell storage Structure membrane sac small food particle vacuole filled w/ digestive enzymes vesicle vesicle filled w/ digested nutrients

Vacuoles have diverse functions in cell maintenance membrane-bound sacs with varied functions. Food vacuoles, from phagocytosis, fuse with lysosomes. Contractile vacuoles, found in freshwater protists, pump excess water out of the cell. Central vacuoles are found in many mature plant cells.

Food & water storage plant cells animal cells food vacuole central vacuole animal cells contractile vacuole

cytoplasm jelly-like material holding organelles in place vacuole & vesicles transport inside cells storage cell membrane cell boundary controls movement of materials in & out recognizes signals

Lysosomes Function digest food clean up & recycle Structure used to make energy clean up & recycle digest broken organelles Structure membrane sac of digestive enzymes Lysosomes lysosomes digesting broken organelles vacuole small food particle digesting food

A Job for Lysosomes 6 weeks 15 weeks

Connection: Abnormal lysosomes can cause fatal diseases Lysosomal storage diseases are hereditary They interfere with other cellular functions Examples: Pompe’s disease, Tay-Sachs disease

ENERGY-CONVERTING ORGANELLES

Mitochondria ATP Function Structure in both animal & plant cells make ATP energy from cellular respiration sugar + O2  ATP fuels the work of life Structure double membrane ATP in both animal & plant cells

cytoplasm jelly-like material holding organelles in place lysosome food digestion garbage disposal & recycling vacuole & vesicles transport inside cells storage mitochondria make ATP energy from sugar + O2 cell membrane cell boundary controls movement of materials in & out recognizes signals

Plants make energy two ways! ATP Mitochondria make energy from sugar + O2 cellular respiration sugar + O2  ATP Chloroplasts make energy + sugar from sunlight photosynthesis sunlight + CO2  ATP & sugar ATP = active energy sugar = stored energy build leaves & roots & fruit out of the sugars sugar ATP

Chloroplasts found in plants and some protists convert solar energy to chemical energy in sugars

Mitochondria are in both cells!! animal cells plant cells chloroplast mitochondria

cytoplasm jelly-like material around organelles central vacuole storage: food, water or waste cell wall support mitochondria make ATP in cellular respiration lysosome digestion & clean up chloroplast make ATP & sugars in photosynthesis cell membrane cell boundary controls movement of materials in & out recognizes signals

2. Cells need workers = proteins! Making proteins to run daily life & growth, the cell must… read genes (DNA) build proteins structural proteins (muscle fibers, hair, skin, claws) enzymes (speed up chemical reactions) signals (hormones) & receptors organelles that do this work… nucleus ribosomes endoplasmic reticulum (ER) Golgi apparatus

Proteins do all the work! one of the major job of cells is to make proteins, because… proteins do all the work! structural enzymes signals receptors DNA proteins cells

Nucleus Function Structure control center of cell protects DNA instructions for building proteins Structure nuclear membrane nucleolus ribosome factory chromosomes DNA

cytoplasm jelly-like material holding organelles in place nucleolus produces ribosomes lysosome food digestion garbage disposal & recycling vacuole & vesicles transport inside cells storage nucleus protects DNA controls cell chromosomes DNA mitochondria make ATP energy from sugar + O2 cell membrane cell boundary controls movement of materials in & out recognizes signals

Ribosomes Function Structure protein factories read instructions to build proteins from DNA Structure some free in cytoplasm some attached to ER Ribosomes on ER

cytoplasm jelly-like material holding organelles in place nucleolus produces ribosomes lysosome food digestion garbage disposal & recycling vacuole & vesicles transport inside cells storage nucleus protects DNA controls cell mitochondria make ATP energy from sugar + O2 ribosomes build proteins cell membrane cell boundary controls movement of materials in & out recognizes signals

Endoplasmic Reticulum Function works on proteins helps complete the proteins after ribosome builds them makes membranes Structure rough ER ribosomes attached Make membranes smooth ER Synthesizes lipids

cytoplasm jelly-like material holding organelles in place lysosome food digestion garbage disposal & recycling vacuole & vesicles transport inside cells storage nucleus protects DNA controls cell mitochondria make ATP energy from sugar + O2 ribosomes builds proteins ER works on proteins makes membranes cell membrane cell boundary controls movement of materials in & out recognizes signals

Golgi Apparatus Function Structure finishes, sorts, labels & ships proteins like UPS headquarters shipping & receiving department ships proteins in vesicles “UPS trucks” Structure membrane sacs vesicles carrying proteins transport vesicles

cytoplasm jelly-like material holding organelles in place lysosome food digestion garbage disposal & recycling vacuole & vesicles transport inside cells storage nucleus protects DNA controls cell mitochondria make ATP energy from sugar + O2 ribosomes builds proteins ER helps finish proteins makes membranes Golgi apparatus finishes, packages & ships proteins cell membrane cell boundary controls movement of materials in & out recognizes signals

nucleolus make ribosomes endoplasmic reticulum processes proteins makes membranes nucleus control cell protects DNA ribosomes make proteins cytoplasm jelly-like material around organelles central vacuole storage: food, water or waste Golgi apparatus finish & ship proteins cell wall support mitochondria make ATP in cellular respiration lysosome digestion & clean up chloroplast make ATP & sugars in photosynthesis cell membrane cell boundary controls movement of materials in & out recognizes signals

3. Cells need to make more cells! Making more cells to replace, repair & grow, the cell must… copy their DNA make extra organelles divide the new DNA & new organelles between 2 new “daughter” cells organelles that do this work… nucleus centrioles

Centrioles Function Structure help coordinate cell division only in animal cells Structure one pair in each cell

cytoplasm jelly-like material holding organelles in place lysosome food digestion garbage disposal & recycling vacuole & vesicles transport inside cells storage nucleus protects DNA controls cell centrioles cell division ribosomes builds proteins ER helps finish proteins makes membranes mitochondria make ATP energy from sugar + O2 Golgi apparatus finishes, packages & ships proteins cell membrane cell boundary controls movement of materials in & out recognizes signals

THE CYTOSKELETON The cell’s internal skeleton that functions in cell structural support and motility A network of protein fibers makes up the cytoskeleton

three main types of fibers in the cytoskeleton: microtubules, microfilaments, and intermediate filaments. Microfilaments enable cells to change shape and move Intermediate filaments reinforce the cell and anchor certain organelles Microtubules give the cell rigidity provide anchors for organelles act as tracks for organelle movement INTERMEDIATE FILAMENT MICROFILAMENT MICROTUBULE

Cilia and flagella locomotor appendages that protrude from certain cells Clusters of microtubules drive the whipping action of these organelles

Cell Summary Cells have 3 main jobs make energy make proteins need food + O2 cellular respiration & photosynthesis need to remove wastes make proteins need instructions from DNA need to chain together amino acids & “finish” & “ship” the protein make more cells need to copy DNA & divide it up to daughter cells Our organelles do all those jobs!