Atoms to Ecosystems

1
Atoms to Ecosystems
Today Biological Building Blocks Our Cells!

• Reminders
• Our fist lab is tomorrow, Wednesday. Be sure to
  bring and prepare your lab notebook!
• Our first group quiz is also tomorrow! Its a
  warm-up, but be sure to review the material we
  work through today.

2
Your First Challenge
What sort of key functions will your space
station need to support life? What types of
structures might accomplish these functions?
Form a group and design your space station using
the whiteboards!
3
Comparing and Contrasting Prokaryotic and
Eukaryotic Cells
Quick Think, Pair, Share Can you come up with
three organisms that are made of prokaryotic
cells? Three that are made of eukaryotic cells?
4
Prokaryotic Cell Structure
5
Basic Cell Structure Eukaryotes
6
All Cells The Plasma Membrane
7
Plasma Membranes Phospholipids
What do you notice about the structure of this
molecule?
8
Plasma Membranes Structure and Function
9
All Cells Ribosomes

• Ribosomal RNA Ribosomal Proteins Ribosomal
  Subunits
• Each Ribosome composed of 2 subunits
• Ribosomes synthesize Proteins, may be free or
  bound

10
Eukaryotic Cells The Nucleus
11
Eukaryotic Cells The Nucleus

• Double-membrane envelope
• Envelope perforated by pores
• Pores lined with pore complex proteins
• Nuclear Lamina lines the inside of the envelope
• Network of filaments, the nuclear matrix, extends
  through interior

12
Within the Nucleus

• DNA is organized around proteins to form
  chromatin
• Ribosomal RNA synthesis occurs in the dense
  nucleolus

13
Eukaryotic CellsThe Endoplasmic Reticulum (ER)
(Part of the Endomembrane System)
14
The Endoplasmic Reticulum

• ER is continuous with the nuclear envelope
• Composed of a systems of sacs called the
  cisternae, enclosing the cisternal space
• Can be smooth or rough

Has Ribosomes! Manufactures proteins for
excretion in transport vesicles, can serve as
membrane factory
No Ribosomes- Synthesizes lipids, detoxifies,
aids in metabolism of carbohydrates, etc.
15
The Endoplasmic Reticulum
16
Eukaryotic Cells The Golgi Apparatus
(also part of the Endomembrane System)
17
Eukaryotic Cells The Golgi Apparatus

• Vessicles transported to the Golgi after leaving
  the ER
• Composed of a stack of flattened membrane sacs
  called cisternae
• Each stack has two sides, the cis (receiving)
  face, and the trans (shipping) face
• Products labeled and modified while traveling
  from cis to trans

18
Lysosomes

• Membrane bound sac of hydrolytic enzymes

• pH 5
• Important in Phagocytosis and Autophagy
• Also part of the Endomembrane System

19
Eukaryotic Cells Vacuoles

• Any large vessicle may be called a vacuole
• Vacuoles are also part of the endo-membrane
  system

20
The Endomembrane System
21
Eukaryotic Cells Mitochondria
22

• Characteristics
• Enclosed by two membranes Outer is smooth,
  inner is folded into cristae
• This creates two spaces, the intermembrane space
  and the mitochondrial matrix
• Semi-autonomous! (Divide and reproduce have
  their own DNA!)

23
Plant Cells Chloroplasts
Specialized Plastid containing the green pigment
chlorophyll, enzymes, and other molecules for
photosynthesis
24

• Components Terminology
• Two membranes, separated by intermembrane space
• Internal system of flattened sacs called
  thylakoids
• A stack of thylakoids is called a granum
• Thylakoids are surrounded by fluid, the stroma,
  containing chloroplast DNA, ribosomes, and
  enzymes!!

25
Explaining the Origins of Mitochondria and
Chloroplasts
??
26
Explaining the Origins of Mitochondria and
Chloroplasts
27
Other Types of Plastids Found in Plants

• Chromoplasts
• Leucoplasts

28
Peroxisomes

• Specialized metabolic compartment
• Single membrane
• Transfer hydrogen to oxygen to make peroxide
  (toxic!)
• Peroxide broken down into water

29
Next The Cytoskeleton

• A network of fibers extending through the
  cytoplasm
• Provides structural support, cell motility, and
  regulation

30
The Cytoskeleton

• 3 types of fibers
• 1. Microtubles (thickest)
• 2. Microfilaments (thinnest)
• 3. Intermediate filaments

31
The Cytoskeleton Microtubules

• In cytoplasm of all eukaryotic cells
• Hollow rods about 25 nm in diameter
• Made of the globular protein, tubulin

32
Functions of Microtubules

• Provide shape and support to the cell
• Serves as tracks along which motor proteins can
  move
• Help separate chromosomes during cell division
• Important components of cilia and flagella

33
Functions of Microtubules
34
Functions of Microtubules
35
Structure of Microtubules
36
Microtubules Dynein walking in cilia and
flagella(Structure and Function!)
37
Origins of Microtubules

• Microtubules often grown out from a centrosome
  (region near the nucleus)
• In animal cells, centrioles in the centrosome,
  give rise to microtubules

38
The Cytoskeleton Microfilaments (2)

• Also called actin filaments
• Solid rods (7nm) of the globular protein, actin
• Each actin chain is twisted into a double chain

39
The Cytoskeleton Microfilaments (2)

• Structural role bears tension
• Often form a network just inside the plasma
  membrane, supporting cell shape
• Play key roles in microvilli, muscle cell
  contraction, amoeboid movement, and cytoplasmic
  streaming

40
Microfilaments in Amoeboid Movement
41
(No Transcript)
42
Microfilaments in Cytoplasmic Streaming
43
The Cytoskeleton Intermediate Filaments (3)

• Diameter 8-12 nm
• Bear tension
• Constructed of different types of keratins
• More permanent in the cell
• Secures nucleus, makes up the nuclear lamina

44
Help! Were running out of coffee
Connections to your Space Station? Other
Structures or Functions??
45
Next Cell Surfaces

1. What functions must ALL cell surfaces accomplish?
2. What structural differences do you notice about
   these two cell types?

46
The Plant Cell Wall
47
The Cell Surface of Animal Cells

• No cell wall!
• Have an extracellular matrix (ECM) composed
  primarily of glycoproteins (esp. collagen)
• Another glycoprotein, fibronectin, attaches cells
  to the ECM by binding at receptor proteins
  (integrins).
• Integrins can transmit signals into the cell!

48
The Cell Surface of Animal Cells
49
Intercellular Junctions in Animal Cells

• 3 Types
• 1. Tight Junctions membranes fused,
  preventing leaking across a layer of cells
• 2. Desmosomes or anchoring junctions connect
  cells in strong sheets (like rivets)
• 3. Gap Junctions provide channels for small
  molecules to pass from one cell to the next

50
Intercellular Junctions in Animal Cells
51
The Dynamic Cell Membrane Setting the Stage
Hmm I wonder what its made of??
In 1895, Charles Overton notices that lipid
soluble compounds enter cells more readily.
52
Overtons Hypothesis Confirmed

• Membranes made of lipids and proteins (1915)
• 1917- artificial membranes made from
  phospholipids
• 1925-Gorter and Grendel propose that the membrane
  is two molecules thick (a phospholipid bilayer)

Needed a MODEL for how the molecules work
together!
53
Model 1 The Davson-Danielli Model (1935)

• Two Problems
• Not all membranes look alike!
• Membrane proteins usually have hydrophobic and
  hydrophillic regions

54
Model 2 The Fluid Mosaic Model (1972)
55
The Fluid Mosaic Model
56
The Fluid Mosaic Model
57
The Fluid Mosaic Model
(Confirmed by Freeze-Fracture)
58
The Fluid Mosaic Model
59
Origins of Membrane Proteins
Result Membranes have an inside and an
outside