Transcript Cell Structure and Function.

Cell Structure
and Function
Attributes of cells

A. Plasma membrane

B. DNA

C. Cytoplasm

D. Obtain energy and nutrients
from their environment
Attributes of cells

Cell size
•
1. 1–100µm (0.00004 – 0.004 inches)
•
2. Why is there a limit to cell size?
• a. Surface-to-volume ratio
• b. Distance from surface to center
tallest trees
adult human
chicken egg
frog embryo
most eukaryotic cells
mitochondrion
most bacteria
virus
proteins
diameter of DNA
double helix
atoms
Attributes of cells

Cell types

1. Prokaryotic—no
nucleus, circular DNA,
ribosomes

2. Eukaryotic—larger,
nucleus, linear
chromosomes,
membranous organelles
Prokaryotic Cells




Have no membrane-bound
organelles
Include true bacteria
On earth 3.8 million years
Found nearly everywhere


Spores in each breath;
intestines
Naturally in soil, air, hot
springs
nucleoid (DNA)
ribosomes
food granule
prokaryotic
flagellum
plasma membrane
cytoplasm
cell wall
Eukaryotic Cells

Have numerous internal structures

Various types & forms


Plants, animals, fungi, protists
Multicellular organisms
nuclear pore
chromatin (DNA)
nucleus
nucleolus
nuclear envelope
flagellum
rough endoplasmic
reticulum
cytoplasm
intermediate
filaments
plasma
membrane
ribosome
lysosome
microtubules
smooth endoplasmic
reticulum
Golgi
complex
free ribosome
vesicle
mitochondrion
vesicle
microtubules
(part of cytoskeleton)
mitochondrion
chloroplast
Golgi complex
central vacuole
smooth endoplasmic
reticulum
vesicle
cell wall
rough endoplasmic
reticulum
plasma
membrane
nucleolus
nucleus nuclear pore
chromatin
nuclear envelope
intermediate
filaments
ribosomes
free ribosome
Eukaryotic cell structure

Nucleus is control center of the cell

1. Membrane bound (nuclear envelope)

2. Contains nucleoli; synthesizes ribosomal RNA

3. DNA in chromosomes (DNA and proteins)
nuclear
envelope
nucleolus
nuclear
pores
chromatin
nucleus
nuclear
pores
chromatin
chromosome
0.05 micrometers
Eukaryotic cell structure

Organelles
Endoplasmic reticulum consists of
folded membranes attached to the
nucleus
Rough ER is site of protein synthesis and
protein secretion
rough endoplasmic reticulum
ribosomes
0.5 micrometers
smooth endoplasmic reticulum
0.5 micrometers
vesicles
Eukaryotic cell structure
Organelles (cont.)
•
Ribosomes assemble amino acid
monomers into polypeptide chains
• a. Associated with the ER
• b. Composed of RNA and proteins
ribosomes
rough endoplasmic reticulum
0.5 micrometers
vesicles
smooth endoplasmic reticulum
0.5 micrometers
Eukaryotic cell structure

Organelles (cont.)

Golgi apparatus are membranous sacs
associated with ER
• a. Processing and transport of proteins, lipids
• b. Synthesis and transport of
polysaccharides
vesicles
from ER
vesicles
leaving
Golgi
complex
Golgi
complex
Eukaryotic cell structure

Organelles (cont.)

Lysosomes are Golgi-derived vesicles
containing digestive enzymes
vesicles
from ER
vesicles
leaving
Golgi
complex
Golgi
complex
Eukaryotic Cells: Organelles
Energy sources for cell activities

Mitochondria provide energy for cellular
functions (respiration)
• a. Membrane bound, numerous
• b. Matrix/cristae
• c. Have their own DNA and
ribosomes; self-replicate
5 micrometers
Eukaryotic Cells: Organelles
Energy sources for cell activities
•
Chloroplasts—function in photosynthesis

1) Green—contain chlorophyll pigment

2) Stroma/grana (thylakoid stacks)
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3) Have their own DNA and ribosomes;
self-replicate
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4) Up to 100 per cell
Eukaryotic Cells: Organelles

Cytoskeleton
 Internal

infrastructure
Surface structures


extensions of the plasma membrane
aid in movement of simple organisms
actin
subunits
subunit
tubulin
subunit
Prokaryotes & Eukaryotes

Similarities & differences

Both surrounded by plasma membrane,
but very different

Prokaryotes – Archaebacteria and
Eubacteria

Eukaryotes – everything else
Evolution of Eukaryotic cell
Endosymbiotic Hypothesis
Similarities between bacteria, mitochondria and chloroplasts
Self-reproducing by binary fission
Size of organism and genome
Single circular naked DNA
Proportion of (G & C) to (A & T)
Same sized ribosome
Protein synthesis inhibited by antibiotics
Enzymes for synthesis of DNA, RNA and protein
Electron transport system
Plant & Animal Cells

Similarities

Both constructed from eukaryotic cells
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Both contain similar organelles

Both surrounded by cell membrane
Plant & Animal Cells
 Differences
 Plants
have
• Cell wall – provides strength & rigidity
• Have chloroplasts, photosynthetic
 Animals
have
• Other organelle not found in plants
(lysosomes formed from Golgi)
• Centrioles, important in cell division
Brief Look at Viruses
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Viruses are acellular
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Not considered to be living
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Cause serious diseases in most
organisms