Cells Unit 4

Development of Cell Theory Anton van Leeuenhoek -1600’s ,developed 1st microscope. Saw tiny things in a drop of water. Robert Hooke- looked at cork. Saw tiny squares that looked like the monks rooms- called them cells. Actually saw the plant cell wall. Robert Brown- first to see cell nucleus

Matthias Schleiden- proved all plants were made of cells Theodor Schwann- proved all animals made of cells Rudolf Virchow- showed that cells come from other cells dividing. Ideas led to………

The Cell Theory All living things composed of cells Cells are basic unit of structure All cells come from pre existing cells.

Microscopes Compound Light M.- uses light. Can magnify up to 1000x. Electron microscopes- uses beam of electrons. Specimen must be viewed in vacuum( no air- so specimen dead!) Scanning EM- scans the surface- gives 3D picture Transmission EM- can see inside cell.

2 Types of cells Prokarotes Eukaryotes

Prokaryotes Do not have membrane bound organelles: no nucleus. Bacteria

Eukaryotes Have membrane bound organelles: like a nucleus. Animal cell, plant cell

Cell structure Cells come in many different sizes and shapes because of the function they carry out.

Properties of All Cells Obtain food for energy Excrete wastes Make new living material(growth) Reproduce

Plasma Membrane

Function Controls the internal environment of a cell- decided what moves in and out Maintains homeostasis

Selective permeability allows some molecules to pass through membrane (SEMI PERMEABLE) Molecules can pass through membrane or pass with aid from membrane proteins

Structure PHOSPHOLIPID(sub unit) Glycerol + 2 FA chains+P Phosphate head Fatty Acid tail Hydrophilic head Hydrophobic tail

Fluid Mosaic Model Phospholipid bilayer- 2 rows of phospholipids with the tails facing each other (pg 177) Phospholipids moveable Mosaic- made of different parts- Membrane proteins-transport materials through,also act as cell receptors for recognition Cholesterol-helps keep fatty acid tails from sticking together- helps maintain fluidity

Cell structure with a specific function and shape ORGANELLES Cell structure with a specific function and shape

CELL WALL Found in plant cells Provides rigidity and strength Made of cellulose Pectin glues the cells together

NUCLEUS Controls cell functions Surrounded by nuclear membrane(has pores) Contains DNA (chromatin ) has instructions(genes) for all cell metabolism like making proteins Chromosomes are made of long strands of chromatin that are condensed

NUCLEOLUS Found inside the nucleus Makes ribosomes

RIBOSOMES Made of RNA Site of protein production Not membrane bound Found in the cytoplasm(free) And also on the RoughER (bound) Made of RNA

CYTOPLASM Clear gelatinous fluid inside cell Suspends the organelles Site of metabolic reactions

ENDOPLASMIC RETICULUM Folded membrane Rough ER has ribosomes attached-make proteins that are used oustide of the cell Unbound ribosomes make proteins used inside the cell Act as transport channels to move material within the cell Packages proteins in small vessicles to move to Golgi

Golgi Apparatus Flattened stack of membranes Modifies proteins-specializes them Packages proteins so they can leave the cell

VACUOLES Compartments used for temporary storage Can store waste, food, enzymes Plant cell has 1 large vacuole to store water

Plastids Found in plants Used to store food and pigments Plastid that store pigment is a chromoplast (chlorophyll/chloroplast)

LYSOSOME Only found in animal cells Contains digestive enzymes Digest worn out cell parts, food, engulfed bacteria and viruses Membrane surrounding lysosome prevents leakage of digestive enzyme into cytoplasm where it would self- digest the cell Can fuse with food vacuole to digest food. What would happen to a cell if the lysosomes burst?

CHLOROPLAST Only found in plant cells Capture light energy and turn it into chemical energy Contains chlorophyll 3 parts: thylakoid-disc granum-stack stroma-inner space

MITOCHONDRIA Power house of the cell Makes ATP Adenosine Triphosphate # of mitochondria depend on energy needs of cell-ex. Muscle cells have a lot! Glucose is changed to ATP at the inner folds(cristae) Cellular Respiration

CYTOSKELETON Microtubules and Microfilaments Microtubules- hollow Microfilaments- solid- function in cytoplasmic streaming Made of proteins Provide internal support Acts like scaffold Also like a highway in the cell to move materials

Centrioles Found in animal cells only Aids in forming the spindle fibers used during cell division(mitosis) Made of microtubules

CILIA AND FLAGELLA Made of microtubules Cilia- short hair like fibers used for locomotion (paremecium) Flagella- long whip like structure used for locomotion

Transportation of Materials THE CELL Transportation of Materials

Movement of Materials The cell membrane is SEMI PERMEABLE: allows movement of some things in and out Diffusion- movement of materials across a membrane Osmosis- movement of WATER across a membrane Cells want to be at equilibrium(Homeostasis)

TYPES OF DIFFUSION PASSIVE- requires no energy- moves high to low FACILITATED- membrane proteins or carrier molecules help materials cross the membrane. They can’t cross on their own. ACTIVE- energy required- moves low to high(you are pushing more into the cell)

PASSIVE DIFFUSION

FACILITATED DIFFUSION

ACTIVE DIFFUSION

Hypotonic- cell or solution has less molecules Hypertonic- cell or solution has more molecules Isotonic- cell or solution has equal molecules

Cell shrinks and shrivels Animal Cell Type Movement of Water Fate of Cell Picture HYPOTONIC Into cell Cell swells and bursts HYPERTONIC Out of Cell Cell shrinks and shrivels LYSES ISOTONIC No net change HOMEOSTASIS

ANIMAL CELL

PLANT CELL

Movement of large material across cell membrane-requires energy Endocytosis- cell surrounds material and engulfs it. Phagocytosis: taking in a solid Pinocytosis: taking in a liquid

cell expels material EXOCYTOSIS 1. Material contained in a vacuole 2. Vacuole moves toward outer edge 3. Vacuole opens up to outside and releases material