Chapter 4 Cell Structure and Function 1 What

Chapter 4 Cell Structure and Function

1. What is a cell? z A cell is the smallest unit that can carry on all of the processes of life.

2. Early scientists that led to the cell theory: y Anton van Leeuwenhoek (1600 s) – given credit for developing the 1 st mini microscope, looked at pond water and made detailed drawings y Robert Hooke – coined the term “cell” when he looked at slices of cork and dead plant cells y Robert Brown (1833) – observed a dark structure near the center of the cell (we now know this is the nucleus) y Matthias Schleiden (1838) – stated all plants are made of cells y Theodor Schwann (1839) – discovered all animals are made of cells y Rudolph Virchow (1855) - stated all cells come from the division of preexisting cells

3. Cell Theory y All living things are composed of cells. y Cells are the basic units of structure and function in living things. y All cells come from preexisting cells.

4. 8 Characteristics that all living things share z Consist of organized parts (cells) z z z z Obtain energy from their surroundings Perform chemical reactions Change with time (evolution) Respond to their environments Reproduce Maintain constant internal environment (homeostasis) Share a common history

5. Relationship between a cell’s shape and it’s function Nerve cells: communication x Diversity of shape reflects diversity of functions x Can be simple or complex depending on its function x Cell shape evolved to allow the cell to perform its function effectively Blood cells: transport Skin cells: protection

6. What factor limits the size that most cells are able to obtain? x Limited by the relationship of the cell’s outer surface area to its volume x Most cells range from 10 -100µm

7. What is the problem with cells getting too large? z. As a cell grows, it’s volume increases much faster than its surface area z. The surface area (the membrane) would not allow materials to enter or leave the cell quickly enough to meet the cell’s needs. z. Therefore, most cells are microscopic in size.

8. Three Basic Parts of the Cell: z Plasma Membrane – regulates what enters and leaves the cell z Cytoplasm – the cell site of many chemical reactions of x Material between the cell membrane and the nucleus x Contains the organelles of the cell z Control Center – controls all of the cells activities x Either free-floating DNA in center of the cell (Prokaryotes) OR a membrane bound organelle called a nucleus (Eukaryotes)

9. Two basic types of cells y Prokaryotes – organisms whose cells lack nuclei and other organelles (i. e. bacteria) y Eukaryotes – organism whose cells contain nuclei and other organelles Pro- = before Eu- = true -karyon = kernel/nucleus

10. What is an organelle? z A well-defined, intracellular body that performs specific functions for the cell. y Ex/mitochondrion produces energy (in the form of ATP) for the cell

Prokaryote vs. Eukaryote Typical Prokaryote (a bacterium):

11. Prokaryote vs. Eukaryote Characteristic Prokaryotic Eukaryotic Cell membrane Cytoplasm Genetic Material Nucleus Organelles Archaea Bacteria Plants, animals, fungi, & protists (only ribosomes)

11. Units of Organization CELLS TISSUE ORGANS ORGAN SYSTEM ORGANISM

12. PROKARYOTIC CELL DIAGRAM PILI – used for attachment to surfaces CELL MEMBRANE – Regulates what enters and leaves CELL WALL – protection RIBOSOME – makes proteins DNA – controls all cells activities FLAGELLA – moves the cell

Animal Cell Nucleolus Rough ER lysosome Nucleus cytoplasm Nuclear envelope mitochondria ribosomes Cell (Plasma) membrane Golgi apparatus Smooth ER

Plant Cell *’s = organelles only found in plant cells, NOT animal cells Nuclear envelope Nucleolus Nucleus Golgi Apparatus * Cell Wall * Rough ER Smooth ER * Central Vacuole * Mitochondria Cytoplasm Cell (Plasma) membrane * Chloroplast *

Cell Membrane – outer boundary y In plants & animals y Structure: x Phospholipid bilayer • hydrophilic heads, hydrophobic tails x Contains lipids (bilayer), proteins (channels), and carbohydrate chains (identification cards) y Function: x Regulates what enters and leaves the cell x Semi-permeable membrane x Protection and support

Nucleus - control center z In plants and animals z Structure: y Genetic material called chromatin (DNA + proteins) z Function: y Information center of the cell y Protects DNA y Directs/controls cell activities

Nucleolus z In plants & animals z Structure: y Made of RNA + proteins y Small, darkened region inside of nucleus z Function: y where ribosomes are made

Mitochondria z In plants & animals z Structure: y. Double membrane x. Cristae - inner folds, increase surface area x. Outer membrane for protection of organelle z Function: y“Powerhouse” of the cell – produces ATP’s (cell energy) y. Able to self-replicate ( # in cells with high energy need) y. Releases energy from food for the organism to use in the process of cellular respiration

Ribosomes z In plants & animals z Structure: y Little “dots” y Small (25 nm) ball-like structures y Found free-floating in cytoplasm or attached to rough endoplasmic reticulum y Composed of RNA and protein z Function: y Synthesis of proteins (where proteins are made)

Endoplasmic Reticulum z In plants & animals z Structure: y Network of flattened sacs y Can be rough (w/ ribosomes) or smooth (w/o ribosomes) z Function: y Transport materials within or out of cell – intracellular highway y Synthesis of macromolecules x. Rough - proteins, lipids, carbs x. Smooth - lipids

Lysosome z In animals only z Structure: y Small, circular structures y Found only in animal cells y Contain digestive enzymes z Function: y Digestion of: x. Worn out organelles x. Debris x. Large ingested particles y Lysosomes are responsible for your hands not being webbed!!

Golgi Apparatus z In plants & animals z Structure: y Flattened stacks of membranes that are not connected y Vesicles fuse with Golgi and get released from Golgi z Function: y Collection, modification, packaging of proteins and other substances x. Vesicles attach, deposit materials x. Golgi modifies materials based on needs x. Vesicles attach to membrane and distribute modified substances

Vacuole z In plants - 1 large, central z In animals – several small z Function: y Storage of water, salts, proteins, carbohydrates, waste products y Pressure system for plants, prevents wilting y Special vacuole: contractile vacuole prevents excess water intake, leading to cell-bursting found in freshwater PROTISTS like a paramecium

Cell Wall – z Only in plants, bacteria, fungi z Structure - y y y z Lies outside the cell membrane Made of fibers of cellulose (plants) Very porous Function y y Helps to protect and support the cell Gives rectangular shape to plant cells

Chloroplasts z Only in plants z Structure: y Inner membranes (thylakoids) surrounded by an outer membrane z Function: y Conversion of light energy (sun) into chemical energy (glucose/food) during the process of PHOTOSYNTHESIS y Other Plastids: y Chromoplasts – Store pigments (ex. carrot root cells, flower petals) y Amyloplasts - Store food/starch

Cytoskeleton - framework z In plants – microtubules, intermediate filaments, microfilaments z In animals – all z Function: maintains cell shape and provides internal support y Microtubules - hollow tubes of proteins, hold organelles in place, maintain shape, act as tracks that guide organelle movement y Intermediate filaments – rods that anchor organelles in place y Microfilaments – long & threadlike, used for cell movement y Cilia – short, hairlike projections used for cell movement y Flagella – long, taillike projections used for movement y Centrioles – organize microtubules during cell division

Who Am I? (quick review) z I stated all plants are made of cells z I stated all cells come from the division of preexisting cells z I coined the term “cell” when I looked at slices of cork and dead plant cells z I am given credit for developing the 1 st mini microscope and I looked at pond water and made detailed drawings z I discovered all animals are made of cells

z. List 3 organelles you learned about today. z. Describe the function of each of the organelles you listed. z. Yes, you should write your name on the paper