1. Cell
Organelles

2. Cell Theory Virchow, Schleiden and Schwann
Every organism is composed of one or more cells
Cells are the smallest units having properties of life
Continuity of life arises from growth and division of single cells
- Cells arise only from pre-existing cells.

3. How many cells in your body?
50 million million (trillion)
That’s 50,000,000,000,000 cells!!!!!!
And not only that, there are many different types.
Cells are diverse
But only two basic types

4. Two Basic Cell Types Prokaryote Eukaryote Pro = before
Name
Pro = before
karyote = nucleus
Eu = true
Relative size
very small
large
True Nucleus present No
yes
Organelles Present
Yes
DNA structure
loose, sometimes circular
packed into chromosomes
Examples
Bacteria
Plants, animals, protists

5. Prokaryotic Cell
Note the lack of nucleus, DNA free floating (nucleoid area)
DO HAVE plasma membrane, ribosomes, and cell wall (sometimes)

6. Endosymbiotic Theory
It is believed that eukaryotic cells arose from groups of prokaryotic cells living together.
Smaller ones inside larger ones.

7. EVIDENCE… For Endosymbiosis
Some eukaryotic organelles resemble bacteria
Mitochondria and Chloroplast – double membrane
Mitochondria and bacteria have similar size
Mitochondria and Chloroplast DNA circular like Bacteria
Mitochondria divide as bacteria do

8. Eukaryotic Cell More Advanced, larger & have organelles
DO HAVE nucleus, ribosomes, mitochondria, chloroplasts (plants), cell wall (plants), endoplasmic reticulum, golgi complex, lysosomes, and vacuoles

9. Eukaryotic Cell
Lots of internal membrane-bound structures!

10. Why are cells so small?
Cells exchange all materials with their environment through the cell membrane.
Exchange is faster in a smaller cell.
Need a surface area proportional to their volume – Surface area to volume ratio decreases as cell gets larger.
Cells that are specialized for absorption have folds in plasma membrane to increase surface area

11. Plasma Membrane

12. Plasma Membrane
Both prokaryotic and eukaryotic cells have this “outer wall”
Holds the CYTOPLASM inside the cell
Gives cells their shape and flexibility
Helps to maintain HOMEOSTASIS by allowing substance to flow in and out of the cell – SELECTIVE PERMIABILITY

13. Structure of Plasma Membrane
The plasma membrane is a PHOSPHOLIPIID BILAYER
PHOSPHOLIPID BILAYER

14. Structure of Plasma Membrane
Fluid Mosaic Model
Phospholipids, cholesterol, and proteins all flow like the surface of a wavy lake, moving and shifting.

15. What are the structures and functions of the cell membrane?

16. Components of the Cell Membrane
Contains lipids, carbohydrates, and functional proteins
Phospholipid Bilayer
Double layer of phospholipid molecules:
hydrophilic heads—toward watery environment, both sides
hydrophobic fatty-acid tails—inside membrane
Membrane Proteins
Integral proteins:
within the membrane
Peripheral proteins:
inner or outer surface of the membrane

17. Cytoplasm All materials inside the cell and outside the nucleus:
cytosol (fluid):
dissolved materials:
nutrients, ions, proteins, and waste products
organelles:
structures with specific functions

18. What are cell organelles & their functions?
Nonmembranous organelles:
no membrane
direct contact with cytosol
Membranous organelles:
covered with plasma membrane
isolated from cytosol
cilia
ribosomes
proteasomes
6 types of nonmembranous organelles:
cytoskeleton
microvilli
centrioles

19. The Cytoskeleton Microfilaments Intermediate
Structural proteins for shape and strength
Microfilaments
Thin filaments composed of the protein actin:
provide additional mechanical strength
interact with proteins for consistency
Pairs with thick filaments of myosin for muscle movement
Intermediate
Mid-sized between microfilaments and thick filaments:
durable (collagen)
strengthen cell and maintain shape
stabilize organelles
stabilize cell position

20. The Cytoskeleton Microtubules Large, hollow tubes of tubulin protein:
attach to centrosome
strengthen cell and anchor organelles
change cell shape
move vesicles within cell (kinesin and dynein)
form spindle apparatus

21. Microvilli
Increase surface area for absorption
Attach to cytoskeleton

22. Centrioles in the Centrosome
Centrioles form spindle apparatus during cell division
Centrosome: cytoplasm surrounding centriole
Cilia Power
Hair-like cilia move fluids across the cell surface

23. Ribosomes Proteasomes
Build polypeptides in protein synthesis
Two types:
free ribosomes in cytoplasm:
proteins for cell
fixed ribosomes attached to ER:
proteins for secretion outside cell
Proteasomes
Contain enzymes (proteases)
Disassemble damaged proteins for recycling

24. Membranous Organelles
5 types of membranous organelles:
endoplasmic reticulum (ER)
Golgi apparatus
lysosomes
peroxisomes
mitochondria

25. Endoplasmic Reticulum (ER)
endo = within
plasm = cytoplasm
reticulum = network
Cisternae are storage chambers within membranes

26. Functions of ER Synthesis of proteins, carbohydrates, and lipids
Storage of synthesized molecules and materials
Transport of materials within the ER
Detoxification of drugs or toxins

27. Smooth Endoplasmic Reticulum (SER)
No ribosomes attached
Synthesizes lipids and carbohydrates:
phospholipids and cholesterol (membranes)
steroid hormones (reproductive system)
glycerides (storage in liver and fat cells)
glycogen (storage in muscles)
Rough Endoplasmic Reticulum (RER)
Surface covered with ribosomes:
active in protein and glycoprotein synthesis
folds polypeptides protein structures
encloses products in transport vesicles

28. Golgi Apparatus Vesicles enter forming face and exit maturing face
Secretory vesicles:
modify and package products for exocytosis
Membrane renewal vesicles:
add or remove membrane components
Transport vesicles:
Carry materials to and from Golgi apparatus
Cis face, closer to ER
Trans face, closer to cell exit

29. Lysosomes Exocytosis Powerful enzyme-containing vesicles:
Primary lysosome:
formed by Golgi and inactive enzymes
Secondary lysosome:
lysosome fused with damaged organelle
digestive enzymes activated
toxic chemicals isolated
Powerful enzyme-containing vesicles:
lyso = dissolve, soma = body
Exocytosis
Ejects secretory products and wastes

30. Lysosome Functions Clean up inside cells: break down large molecules
attack bacteria
recycle damaged organelles
ejects wastes by exocytosis

31. Autolysis Peroxisomes
Self-destruction of damaged cells:
auto = self, lysis = break
lysosome membranes break down
digestive enzymes released
cell decomposes
cellular materials recycle
Peroxisomes
Are enzyme-containing vesicles:
break down fatty acids, organic compounds
produce hydrogen peroxide (H2O2) …TOXIC
replicate by division

32. KEY CONCEPT Cells: basic structural and functional units of life
respond to their environment
maintain homeostasis at the cellular level
modify structure and function over time

33. Mitochondrion Structure
2 Membranes
Have smooth outer membrane and folded inner membrane (cristae)
Matrix:
fluid around cristae

34. Mitochondrial Function
Mitochondrion takes chemical energy from food (glucose):
produces energy molecule ATP

35. Nucleus

36. Nucleus Control Center of the cell Contain CHROMATIN (loose DNA)
Bundles into CHROMOSOMES when cell is ready to divide (it packs before moving)
Chromatin
Chromosomes

37. Chromatin in the Nucleus
Directs PROTEIN SYNTHESIS (building proteins)
It contains the “blueprints”
“Blueprints” are Called DNA
DNA in loose coils called chromatin

38. How does the nucleus control the cell?
largest organelle
Nuclear envelope:
double membrane around the nucleus
Perinuclear space:
between 2 layers of nuclear envelope
Nuclear pores:
communication passages

39. Nucleus Controls Cell Structure and Function
Direct control through synthesis of:
structural proteins
secretions (environmental response)
Indirect control over metabolism through enzymes

40. Within the Nucleus Nucleoli in Nucleus
DNA:
all information to build and run organisms
Nucleoplasm:
fluid containing ions, enzymes, nucleotides, and some RNA
Nuclear matrix:
support filaments
Nucleoli in Nucleus
Are related to protein production
Are made of RNA, enzymes, and histones
Synthesize rRNA and ribosomal subunits

41. Organization of DNA Nucleosomes: Chromatin: Chromosomes:
DNA coiled around histones
Chromatin:
loosely coiled DNA (cells not dividing)
Chromosomes:
tightly coiled DNA (cells dividing)
Figure 3–11

42. What is genetic code? DNA and Genes Genetic Code
instructions for every protein in the body
Gene:
DNA instructions for 1 protein
Genetic Code
The chemical language of DNA instructions:
sequence of bases (A, T, C, G)
triplet code:
3 bases = 1 amino acid

43. KEY CONCEPT The nucleus contains chromosomes Chromosomes contain DNA
DNA stores genetic instructions for proteins
Proteins determine cell structure and function

44. Cell Walls Outside of the plasma membrane
Can be made of thick fibers of cellulose (plants), chitin (fungi), or peptodoglycan (some bacteria)
Plant cells have openings in cell wall called GAP JUNCTIONS for cell to cell communication
Animal cells DO NOT have cell walls

45. Cell Wall of Plants
Is this a prokaryotic or eukaryotic cell?