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Unit 2 Cell Structure and function

Terms in this set (53)

CELL THEORY
All living organisms are composed of cells

All cells come from pre existing cells

Calls are the smallest unit of life
Significance of cell theory
Each cell essentially represents an - organism: a complete functional entity, capable of all - biochemical reactions and self-reproduction.
Why are cells so small?
Cells have greater surface area relative to volume

Greater the surface area: the volume ratio, better the rate of exchange of nutrients and waste materials with the cell's environment
ALLS CELLS HAVE
Plasma membrane
a. Regulate flow of materials in and out of cells

Cytosol
a. Semifluid substance in which other organelles float and chemical reactions form

Chromosome(s)
a. Contain the genetic material

DNA

Ribosomes
a. Involved in protein synthesis
DNA into RNA, then translated into protien
MAJOR CELL STRUCTURES
Nucleus
Ribosomes
Endoplasmic reticulum
Golgi apparatus
Lysosomes
Mitochondria
Chloroplast
Cytoskeleton
Plasma membrane
Nucleus
structure that contains the cell's genetic material (DNA) and controls the cell's activities
Which molecules need to travel into Nucleus
Proteins for DNA replication

Ribosomal proteins for assembly of subunits

Histones for building chromatin/chromosomes
Molecules that travel out of nucleus?
tRNA, mRNA for protein translation
Ribosome
small particle in the cell on which proteins are assembled; made of RNA and protein
What are the two locations of ribosomes
1. Cytosol (FREE )
2. Outside ER or Nuclear envelope
Endomembrane System
Regulates membrane traffic and performs metabolic functions in the cell
Endoplasmic Reticulum
internal membrane system in cells in which lipid components of the cell membrane are assembled and some proteins are modified
Smooth ER
Lacks ribosomes

collection of enzymes that perform specialized tasks, including synthesis of membrane lipids and the detoxification of drugs (Hydroxylation)
Rough ER
proteins that are released, or exported, from the cell are synthesized on the rough ER
Plasma Membrane
Selective barrier that allows sufficient passage of oxygen, nutrients, and waste to service the volume of every cell
What is plasma membrane made out of
double layer of phospholipids
Golgi Complex
stack of membranes in the cell that modifies, sorts, and packages proteins from the endoplasmic reticulum

Release products in vesciles
Lysosomes
cell organelle filled with enzymes needed to break down certain materials in the cell

Old organelles are broken up into proteins
Can also digest pathogens
Vacuoles
cell organelle that stores materials such as water, salts, proteins, and carbohydrates

IN PLANTS, it is the largest compartment
Mitrochondria
cell organelle that converts the chemical energy stored in food into compounds that are more convenient for the cell to use

Glucose + O2----> CO2 + H2O + energy (ATP)
Inner and Outer membrane of mitochondria (phospholipid bilayer)
Outer membrane is more permeable than the inner

inner membrane is folded up into shelves (cristae): increased surface area: many proteins and enzymes are attached here: role in cellular respiration
Chloroplast
organelle found in cells of plants and some other organisms that captures the energy from sunlight and converts it into chemical energy

6 CO2 + 12 H2O + Light energy C6H12O6 + 6 O2 + 6 H2O
What makes plants green
Chlorophyll
Stroma
inner fluid

has own DNA and ribosome
Endosymbiotic Theory
Certain prokaryotes lived within eukaryotes and evolved into mitochondria and chloroplasts
Evidence of Endosymbiotic Theory
1) mitochondrial DNA and chloroplasts contain DNA similiar to bacterial DNA

2) mitochondria and chloroplasts have ribosomes whose size and structure closely resemble those of bacteria

3) like bacteria, mitochondria and chloroplasts reproduce by binary fission while the cells containing them divide by mitosis
Peroxisome
Liver cells
Cytoskeleton
Network of fibers
Function of Cytoskeleton
Organizes cell structure and activities

Helps keep cell shape

Interacts with MOTOR PROTEINS TO PRODUCE MOBILITY
What are the three types of molecular structures
Microtubules, Microfilaments, Intermediate Filaments
Microtubules
CILIA AND FLAGELLA

Hollow tubes

Maintain cell shape

Mobility

Chromosome movement in cell division

Organelle movements
Microfilaments
Two intertwined strands of actin

Maintain cell shape

Muscle contraction

Cell mobility

Cell division

Cytoplasmic streaming, slushing
Intermediate Filaments
Fibrous proteins supercoiled into thicker cables

Maintain cell shape

Anchorage of nucleus and other organelles

Made of proteins such as keratin
What dinstinguishes plant cels from animal cells
Cell wall
What does the Cell Wall do?
protects plant cell from external environment

Maintains its shape and prevents excessive uptake of water
plasmodesmata
Channels between adjacent cells; membrane lined channels containing cytoplasm

Plant cells can be interconnected with one another
What do animals have instead of a cell wall
Extracellular matrix
Extracellular Matrix Function
Support, adhesion, movement and regulation
Plasma Membrane
boundary that separates the living cell from its surroundings
Selective Permeability in Plasma Membrane
Allows some substances to cross more easily
Plasma Membrane Composition
Phospholipids, proteins, carbohydrates
Phospholipids
Head love water (HYDROPHILLIC)

tail hates water (HYDROPHOBIC)
Sandwich effect
Forms a bilayer

Two groups of tails sandwiched towards the interior, one group of Phosphate heads towards the cytoplasm (aqueous), other towards the cells exterior (aqueous)
Fluid Mosaic Model
Cell membrane NOT rigid
Phospholipid are MOBILE (move laterally)

Membranes must be in fluid to move properly
Example of importance of fluidity
If solidified, than membrane cannot function properly

Example: fish that live in extreme cold environments have high proportion of unsaturated phospholipids
Cholesterol
Essential lipid in animal cell membranes
Integral Proteins (membrane proteins)
inserted in membrane
Peripheral Proteins (Membrane proteins)
not embedded in membrane
Bulk Transport
Large molecules cross the membrane in bulk via vesicles which requires ENERGY
Exocytosis
transport vesicles migrate to the membrane, fuse with it, and release their contents
Endocytosis
cell takes in macromolecules by forming vesicles from the plasma membrane
3 Types of endocytosis
PHAGOCYTOSIS (Cellular eating)
PINOCYTOSIS (Cellular Drinking)
Receptor-mediated endocytosis
Nucleus
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