Download Cells and Organelles

 Cell Theory
Cell Size
Function of
Organelles
Cell Theory
 All organisms are composed of one or more
cells
Cells are the basic living unit of structure and
function in organisms
All cells come only from other cells
Cell Size
• Surface Area to Volume Ratio
Surface area affects the ability of nutrients to
get into the cell and wastes to get out
Large cells need more nutrients and produce
more wastes than small cells
Small cells have more surface area per volume
than large cells
Eukaryotic Organelles
• What defines a eukaryotic cell?
Has a nucleus
• How do plant cells differ from animal cells?
 Cell wall
 Primary cell wall Cellulose = strength
 Secondary cell wall  Lignin = even stronger
 Chloroplasts
 Chlorophyll  Photosynthesis
The Outer Boundaries
• Plasma membrane
Composition:
 Phospholipid bilayer with embedded proteins
Function:
 Defines cell boundary
 Regulates entrance and exit of molecules
• Cytoplasm
– Semifluid medium that contains organelles
– Surrounds the nucleus inside the cell
membrane
The Nucleus
Composition:
 Nuclear envelope (Double membrane with
pores)
 Nucleoplasm
 Chromatin (DNA and proteins)
 Nucleoli (Nucleolus)
o Composition: Concentrated area of chromatin, RNA
and proteins
o Function: Ribosomal subunit formation
Function:
Storage of genetic information
 Synthesis of DNA and RNA

View Fig 3.4, p. 52 in your textbook
Composition:
Ribosomes
Protein and rRNA
Two subunits (large and small)
 Very small organelles
Occur in the cytoplasm:
- Singly
- Groups (polyribosomes)
Attached to the
Endoplasmic reticulum
Function:

Protein synthesis
The Endomembrane System
Consists of:
Nuclear envelope
 Endoplasmic
Reticulum
Golgi Apparatus
Lysosomes
Transport Vesicles
The Endoplasmic Reticulum
Composition:
 Membranous, flattened channels, tubular canals
Function:
 Synthesis and/or modification of proteins
+ other substances
Distribution via vesicle formation
The Rough ER
Composition: studded with ribosomes
Function: protein synthesis
The Smooth ER
Composition: having no ribosomes
Function: lipid synthesis and forms vesicles for transport
The Golgi Apparatus
Composition:
 Stack of membranous saccules
Function:
 Processing
 Packaging
Secretion
 Distribution of
proteins and lipids
Formation of lysosomes
Lysosomes
Composition:
 Membranous vesicle produced by Golgi
apparatus
 Contains hydrolytic digestive enzymes
Function:
 Intracellular digestion
 Macromolecules
 Bacteria
 Cell contents
Vacuoles
Composition:
 Large membranous sac
(vacuoles are larger than vesicles)
 Both animals and plant have them, but much
bigger in plants
(in plants: large, central, filled with water, sugar,
salt, pigments, toxins  support, color and
protection)
Function:
 Store substances
Peroxisomes
Composition:
 Membranous vesicles
Contain specific enzymes
Function:
 Various metabolic tasks
 Result in the production of hydrogen
peroxide molecules
Catalase breaks into water and oxygen
Energy-Related Organelles
ATP
CO2 + H2O
Useable energy
for cells
Carbohydrate
Mitochondria
Cellular Respiration:
carbohydrate + oxygen 
Solar energy + carbon dioxide
+water
Chloroplast
Photosynthesis:
Solar energy + carbon dioxide
+water  carbohydrate +
oxygen
Chloroplasts (only in plant cells)
Composition:
Membranous grana bounded by two membranes
 Stroma (fluid filled space with DNA, ribosomes,
enzymes)
 Thylakoids (flattened sacs)  stacked = grana
  contains chlorophyll

Function:
Photosynthesis
Mitochondria
Composition:
 Double membrane
Inner membrane folded= Cristae
Increases surface area for ATP production
Inner fluid filled space = Matrix
 Contains DNA, ribosomes, enzymes to break
down carbohydrates
Function:
Cellular Respiration
(produce ATP)

Composition:
 Microtubules
The Cytoskeleton
 Help evenly distribute chromosomes during cell division
 Maintain shape and help organelles move around
 Intermediate filaments
 Help support nuclear envelope and plasma membrane
 Lends mechanical strength
 Actin filaments
 Structural role
 Formation of Pseudopods
 Movement of cells and organelles (Myosin)
Function:
 Shape of the cell
 Movement of cell parts
Centrioles (only in animal cells)
Composition:
 9+0 pattern of microtubule triplets
Function:
 Formation of basal bodies
organization of cilia + flagella
 Microtubule formation
Composition:
Cilia and Flagella
 9+2 pattern of microtubule doublets, around 2 central microtubules
 Membrane bounded cylinders enclosing a matrix
 Cilia are much shorter than flagella
Functions:
 Movement of the cell
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