Download Ch.4 Notes - Green Local Schools

Cell Structure & Function
Ch.4 & 1-4
(4-1) History
• Cell: smallest unit that can carry on the
processes of life
• Hooke (1665): looked at plants under
microscope & saw “little boxes”
– Named them “cells”
• Leeuwenhoek (1673): 1st to see living cells
Cell Theory
1. All living things are
composed of cells
2. Cells are the basic
unit of an organism
3. Cells only come
from the
reproduction of
existing cells
(4-2) Intro to Cells
• Cell Diversity
– Your body has over 200 different types of
cells
Red Blood Cells
Bacterial Cells
Skin Cells
Cell Size
• Most cells are microscopic
• Limited by surface area to volume ratio
– Larger ratio = more efficient
Surface Area to Volume Ratio
• Surface Area: L x W x # of sides
• Volume: L x W x H
• Ratio: SA / V
Required rate of transport
proportional to Volume, V
Feasible rate of transport
proportional to Surface Area, S
As cell gets larger, V 
faster than S 
Hence, as cells get larger,
desired rate increases
faster than feasible rate.
Cell Shape
• Determined by the function of the cell
Basic Parts of a Cell
• Plasma (cell) membrane: covers cell’s
surface & provides barrier
• Cytoplasm: fluid (cytosol), cytoskeleton, &
organelles inside membrane
– Site of chemical rxns
• Nucleus: control center
Basic Cell Types
Prokaryotic vs. Eukaryotic
• “Before nucleus”
(nucleoid)
• No membrane
organelles
• Single cell organisms
• “True nucleus”
• Membrane organelles
• Multicellular & single
cell organisms
Cellular Organization
• Colonies:
– Identical cells in a connected group
– Not multicellular (few activities coordinated)
• Multicellularity:
– Tissue
– Organ
– Organ system
(4-3) Organelles & Features
• Structures are determined by the functions
of each part
Plasma Membrane
• Function: allows substances into & out of
the cell
• Selectively permeable: allows only certain
things to cross the membrane
Parts of the Membrane
• Membrane lipids
– Phospholipid
bilayer:
hydrophobic &
hydrophilic ends
Parts of the Membrane (cont.)
• Membrane proteins
– Peripheral proteins:
attached to sides
– Integral proteins:
embedded w/in
Fluid Mosaic Model
• Membrane behaves like a liquid
• Mosaic: changing pattern of proteins &
lipids
Nucleus
• Function: store hereditary info
(DNA) & control the cell
• Contains:
– nuclear envelope: surrounds nucleus
– nuclear pores: holes in envelope that allows
material to enter & leave nucleus
– nucleolus: area of concentrated
DNA (chromatin)
Mitochondria
• Function: makes
ATP (E)
• “Powerhouse” of
the cell
• Has own DNA
Rough Endoplasmic Reticulum
(RER)
• Function: makes proteins &
phospholipids, & prepares molecules for
export out of cell
• Attached ribosomes make “rough”
Smooth ER (SER)
• Function: makes lipids & steroid
hormones, metabolizes carbs, regulates
Ca2+ levels, & is detoxification center for
cell
Ribosomes
• Function: makes proteins
Golgi Apparatus
• Function: stores,
sorts, modifies, &
ships materials out
of the cell
Vesicles
• Lysosomes: break down macromolecules
– Release glucose into blood
– Break down bacteria
• Peroxisomes: break down fatty acids
– Detoxification center in liver cells
Cytoskeleton
• Function: support system of the cell; aid in
movement w/in the cell
– Microtubules
– Microfilaments
Cilia & Flagella
• Function: locomotion &
movement of materials
around the cell
• Animal cells only*
(4-4) Plant Cell Organelles
• Cell Wall
• Central vacuole
• Plastids
Cell Wall
• Function: protects the cell; gives shape &
structural support
• Outside cell membrane
• Made of cellulose & proteins
Central Vacuole
• Function: stores
materials such as
water, enzymes, &
waste
• Other vacuoles
store toxins
Plastids
• Have their own membrane & DNA & store
materials (pigments, starch)
• Chloroplasts: plastids that undergo
photosynthesis
(1-4) Microscope
• Instrument that produces an enlarged
image of an object
• Magnification: increase of an object’s size
• Resolution: ability to show details clearly
Light Microscopes
•
•
•
•
•
Stage: where slide is placed
Objective lens: enlarges image
Ocular lens: magnifies image further
Nosepiece: revolves lenses
Power of magnification: factor of
enlargement
– Obj. x ocular = total power of mag.
– Ex: 40X x 10X = 400X
Light Microscope (cont.)
• Diaphragm: adjusts amount of light
• Coarse-adjustment: focuses specimen
• Fine-adjustment: focuses specimen even
more
Electron Microscopes
• Beam of e- produces enlarged image of
nonliving specimen
• More powerful than light microscopes
• 2 types:
– Transmission (TEM)
– Scanning (SEM)