ap biology discussion notes
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AP Biology Discussion Notes. Tuesday 10/7/2014. Goals for the Day. Become familiar with the cell organelles and their functions. Be able to describe the function of specific organelles, and which types of organisms have them Describe how things are transported in/out of the cell. - PowerPoint PPT PresentationTRANSCRIPT
AP Biology Discussion Notes
Tuesday 10/7/2014
Goals for the Day
1. Become familiar with the cell organelles and their functions.
2. Be able to describe the function of specific organelles, and which types of organisms have them
3. Describe how things are transported in/out of the cell
Question of the Day
What is osmosis & what kind of transport would it be considered?
Question of the Day
What is osmosis & what kind of transport would it be considered?
The “tonics”
Hypotonic
Isotonic
Hypertonic
Species of the day 10/6
Curculio spp.
• Acorn Weevil
Species of the day 10/6
Curculio spp.
• Acorn Weevil
Do the acorn and the weevil share the same cell parts? EXPLAIN your answer!
Structures of Plant Cells
Plants have three (for now) unique structures that are not found in animal cells:
• Cell Wall
• Chloroplasts
• Central Vacuole
Cell Wall• Provides Structure and Support• Contains cellulose ( in plants)• Contains _______ in Fungi• Contains ______________ in bacteria• Allows the cell to build pressure
Cell Walls of Plants• The cell wall is an extracellular structure that
distinguishes plant cells from animal cells
• Prokaryotes, fungi, and some protists also have cell walls
• The cell wall protects the plant cell, maintains its shape, and prevents excessive uptake of water
• Plant cell walls are made of cellulose fibers embedded in other polysaccharides and protein
• Plant cell walls may have multiple layers– Primary cell wall: relatively thin and flexible– Middle lamella: thin layer between primary walls
of adjacent cells– Secondary cell wall (in some cells): added
between the plasma membrane and the primary cell wall
• Plasmodesmata are channels between adjacent plant cells
Secondarycell wallPrimarycell wallMiddlelamella
Central vacuoleCytosol
Plasma membrane
Plant cell walls
Plasmodesmata
1 m
Figure 6.28
Plasmodesmata in Plant Cells• Plasmodesmata are channels that
perforate plant cell walls• Through plasmodesmata, water and small
solutes (and sometimes proteins and RNA) can pass from cell to cell
Figure 6.31
Interiorof cell
Interiorof cell
0.5 m Plasmodesmata Plasma membranes
Cell walls
Central VacuoleCentral Vacuole:
Most of a plant cell’s volume is taken up by a large, membrane-bound space called the central vacuole.
The central vacuole stores water and may contain ions, nutrients, and wastes.
Peroxisomes: Oxidation• Peroxisomes are specialized metabolic
compartments bounded by a single membrane• Peroxisomes produce hydrogen peroxide and
convert it to water• Peroxisomes perform reactions with many
different functions
• What does that remind you of???
Figure 6.19
ChloroplastPeroxisome
Mitochondrion
1 m
Chloroplast
• Site of photosynthesis– Light Energy -> Chemical Energy
• Double-membraned• Stacks of thylakoids
Mitochondria
• Generate ATP from glucose– Generate ____________energy
• Site of cellular respiration• Double membraned—cristae
Mitochondria & Chloroplasts• Unique features:
• Both are energy-related organelles
• Have two membranes
• Have their own DNA
• Reproduce independently of the cell
• Have Ribosomes
Endosymbiotic (Endosymbiont)Theory
• What does endo mean?
• What is symbiosis?
Endosymbiotic Theory
• If mitochondria and chloroplasts originally came from independent prokaryotes, what would be true of their DNA? (What do you know about the DNA of prokaryotes compared to Eukaryotes?)
Endosymbiotic Theory
NucleusEndoplasmicreticulum
Nuclear envelope
Ancestor ofeukaryotic cells(host cell)
Engulfing of oxygen-using nonphotosyntheticprokaryote, whichbecomes a mitochondrion
Mitochondrion
Nonphotosyntheticeukaryote
Mitochondrion
At leastone cell
Photosynthetic eukaryote
Engulfing ofphotosyntheticprokaryote
Chloroplast
Figure 6.16
The cytoskeleton is a network of fibers that organizes structures
and activities in the cell• The cytoskeleton is a network of fibers
extending throughout the cytoplasm• It organizes the cell’s structures and activities,
anchoring many organelles• It is composed of three types of molecular
structures– Microtubules– Microfilaments– Intermediate filaments
Figure 6.20
10
m
Roles of the Cytoskeleton: Support and Motility
• The cytoskeleton helps to support the cell and maintain its shape
• It interacts with motor proteins to produce motility
• Inside the cell, vesicles can travel along “monorails” provided by the cytoskeleton
• Recent evidence suggests that the cytoskeleton may help regulate biochemical activities
Figure 6.21
ATPVesicle
(a)
Motor protein(ATP powered)
Microtubuleof cytoskeleton
Receptor formotor protein
0.25 m VesiclesMicrotubule
(b)
Components of the Cytoskeleton• Three main types of fibers make up the
cytoskeleton– Microtubules are the thickest of the three
components of the cytoskeleton– Microfilaments, also called actin filaments,
are the thinnest components– Intermediate filaments are fibers with
diameters in a middle range
Column of tubulin dimers
Tubulin dimer
25 nm
Actin subunit
7 nm
Keratin proteins
812 nm
Fibrous subunit (keratinscoiled together)
10 m 10 m 5 m
Table 6.1
Tubulin dimer
25 nm
Column of tubulin dimers
10 m
Table 6.1a
10 m
Actin subunit
7 nm
Table 6.1b
5 m
Keratin proteins
Fibrous subunit (keratinscoiled together)
812 nm
Table 6.1c
Microtubules• Microtubules are hollow rods about 25 nm in
diameter and about 200 nm to 25 microns long• Functions of microtubules
– Shaping the cell– Guiding movement of organelles– Separating chromosomes during cell division
Centrosomes and Centrioles• In many cells, microtubules grow out from
a centrosome near the nucleus• The centrosome is a “microtubule-
organizing center”• In animal cells, the centrosome has a pair
of centrioles, each with nine triplets of microtubules arranged in a ring
Centrosome
Longitudinalsection ofone centriole
Centrioles
Microtubule
0.25 m
Microtubules Cross sectionof the other centriole
Figure 6.22
Cilia & Flagella
• What would be the function in 1 word?
Organelles Organized
Species of the Day
• Resurrection Plant - Selaginella lepidophylla
• This plant belongs to the Lycophyta and has the oldest known lineage of any VASCULAR plant. Being as this plant represents one of the most primitive vascular plants.
Species of the Day
• Resurrection Plant - Selaginella lepidophylla
• Predict how long it would take for this plant to begin to be active again.