Download BSCI 124: LECTURE 2

BSCI 124 extra-credit project:
1) Please pick up your plant kit bag
2) Fill out Entry Ballot
(yellow paper) to enter
textbook raffle… Fold and
place ballot in the box.
ENTRY BALLOT
BSCI 124
Name: ______________
Major: ______________
Reason for taking this class:
What do you want to get
out of this class?
Do you have any special
Interst in plant biology?
BSCI 124: LECTURE 2
THE AMAZING PLANT CELL
Prof. Edgar Moctezuma, Ph.D.
TODAY…
• Pick up: Your free Plant Project Kit & fill ballot
• Life’s molecules:
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–
–
–
•
•
•
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Carbohydrates
Lipids
Proteins
Nucleic acids
Raffle: borrow a Textbook for free!
What is a cell?
The Cell Theory
Cell components: cell wall, organelles
Endosymbiont Theory
Cell Macromolecules:
The Molecules of Life
The cell is made of the following four biologically
important molecules:
• Carbohydrates (sugars, starches, cellulose)
• Lipids (fats, oils, waxes, phospholipids, steroids)
• Proteins (composed of amino acids)
• Nucleic Acids (DNA, RNA)
Life’s molecules
•
All life’s molecules share the following four
characteristics:
1. Carbon-based
2. Formed from a few elements: C, H, O, N, P
3. Modular construction (like bricks, cheap and
easy to build small building blocks)
4. Their function depends on structure
(or, structure/shape determines function)
Why should we learn about life’s
molecules?
• Because we eat them
everyday!
• We are composed of these
bio-molecules
1. Carbohydrates
• Organic molecules composed of C, H, O
(1:2:1 ratio)
• Most abundant of life’s molecules
Carbohydrates
There are three types of carbohydrates:
Mono- saccharides (one)
Disaccharides (two)
Poly- saccharides (many)
• Monosaccharides
(simple sugars of 3 to 6 carbons)
• Glucose C6H12O6 (‘blood sugar’)
• Fructose C6H12O6 (fruit)
• Ribose C5H10O5 (nucleic acids)
Carbohydrates
• Disaccharides
• Composed of two
monosaccharides.
• Sucrose (table sugar)
C12H22O11
Glucose + Fructose = Sucrose + water
Carbohydrates
• Polysaccharides (many) –
long chains of monosacch.
• Starch – energy storage
• Cellulose – plant cell walls
(wood, paper, cloth)
Function of Carbohydrates
• Energy storage (in the C-H bonds)
• For structure in plants (cellulose for cell wall)
• Carbon sources to make other molecules
(nucleic acids, amino acids)
2. Lipids
• Composed of C, O, H atoms
• Fats and oils are made from two building
blocks:
• Glycerol molecule
(hydrophilic;
‘water loving’)
• Fatty Acids
(hydrophobic;
‘water hating’)
Lipids
• Fats are solid lipids at room temperature
(usually animal-derived: lard, butter)
• Oils are liquid lipids
(usually plant-derived:
corn oil, peanut oil,
olive oil)
Lipids
• Lipids DO NOT dissolve in water
• Phosholipids contain phosphorus
• The membranes of cells is a lipid bilayer
Function of Lipids
•
•
•
•
As a high-energy food
As part of cell membrane
As waxes, hormones, vitamins, pigments
Energy storage of lipids
– Monoglycerides (glycerol + 1 fatty acid chain)
– Diglycerides (monoglyceride + 2nd fatty acid chain)
– Triglycerides (diglyceride + 3rd fatty acid chain)
• Triglycerides = highest energy!
3. Proteins
• Large complex molecules
• Composed of C, H, O, S and N
• Building blocks are amino acids (20)
protein
Ribosome
Function of Proteins
• Building blocks of cells
• Transport: they help control
what passes through
Plasma Membrane
• Animal structure (hair, nails, tendons, muscles)
• Enzymes – to speed up chemical reactions
4. Nucleic Acids
• Nucleic acids are large organic molecules
• Composed of C, H, O, P, N
• Basic unit is
the Nucleotide:
1) a sugar,
2) a phosphate, and
3) a nitrogenous base
Nucleic Acids
• Nucleic acids are long chains of nucleotides
Examples
• DNA : Deoxyribonucleic acid,
carries information about the
entire cell
• RNA: ribonucleic acid,
– a copy of DNA
Nucleic Acids: ATP
• Another nucleotide compound is ATP, which has
a role of energy transfer/exchange (e.g. like an
energy currency)
Function of Nucleotides:
• Information storage (like a blueprint for the cell;
DNA, RNA)
• Energy carrier (ATP)
Life’s molecules
•
All life’s molecules share the following four
characteristics:
1. Carbon-based
2. Formed from a few elements: C, H, O, N, P
3. Modular construction – made from simple building
blocks
1.
2.
3.
4.
Carbohydrates – monosaccharides (sugars)
Lipids – fatty acids
Proteins – amino acids
Nucleic acids – nucleotides
4. Their shape and structure determines their function!
Raffle!
• Borrow one Textbook
• Also ordered a few textbooks on reserve at
the Mckeldin Library
The plant cell
What is a cell?
• Basic building blocks of living organisms
• Form tissues and organs
• Each cell is functionally independent – it can
live on its own under the right conditions
– Uses sugars to get energy and stay alive
– Contains all necessary info to replicate  produce
a multicellular organism
– Can make a whole plant  from a single cell!
The Cell
All plants are composed of cells.
• First discovered by
Robert Hooke in 1665
• Cell Theory:
1) Cell is the basic unit of life
2) Organisms are composed of cells
3) Cells arise from other cells
Two types of cells:
• PROKARYOTIC
• EUKARYOTIC
Simple cells, lack organelles
Bacteria are prokaryotic
10 to 100 times smaller than
animal or plant cells
They have organelles: nuclei, mitoch., etc.
Many multicellular organisms are eukaryotic:
Cells of plants, animals, fungi, are
eukaryotic
Some unicellular organisms are
eukaryotic: algae, amoeba, etc.
Prokaryotes
Older organisms (3.5 byo)
Smaller
No organelles
Eukaryotes
More recent (1.5 byo)
10 – 100 times bigger
Have organelles
THE PLANT CELL: Eukaryotic or prokaryotic?
EUKARYOTIC: HAS ORGANELLES!
Plant vs. animal cells
• Plant cells have 3 things animal cells don’t:
1) Cell walls
2) Vacuoles
3) Chloroplasts
Plant Cells
• Structural building blocks
to form tissues and organs
• Plant cells: potentially can function
independently.
Can even create a whole plant from a
single cell (plant cloning)
THE PLANT CELL: outside
Outside:
Cell wall
Plasma membrane
Cell wall
• Cell wall protects and supports cell
• Is made of CELLULOSE
• Allows water and other
molecules to
pass through
(like a cardboard box)
Primary vs. Secondary cell wall
• Primary wall is formed early,
located on the outermost layer.
• Secondary wall is deposited on the inside,
between Primary cell wall and
Plasma membrane.
• Middle lamella: what ‘glues’ adjacent cells
together.
Cell membrane (or plasma membrane)
• Is a lipid bi-layer: hydrophilic “heads”
(outer), hydrophobic “tails” (inside)
• Differentially permeable:
Lets water pass through,
but not other molecules
Cell membrane (plasma membrane)
• Fluid Mosaic Model:
A double layer of phospholipids with scattered
proteins…
(looks like “protein icebergs in a sea of lipids”)
Inside the Plant Cell:
• Cytosol: a matrix of water (90%), proteins,
organic molecules, ions
• Cytoplasm: cytosol and organelles only
• Protoplast: all of the plant cell enclosed by the
cell wall (plasma membrane, cytosol, organelles)
Cytoskeleton
• Microtubules & microfilaments: Make up
the Cytoskeleton, a network of protein
‘cables’ that provide structure to the cell –
they help in cell division & elongation.
• Important for mitosis
Plant Cell Organelles
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•
Organelles are membrane-bound subcompartments within the cell.
Each has its own function.
1.
2.
3.
4.
5.
6.
7.
Nucleus
Mitochondria
Chloroplast
Vacuole
Ribosomes
Endoplasmic reticulum
Golgi apparatus
Nucleus
Nucleus: contains all genetic information (DNA)
in chromosomes.
Plant nucleus
• Chromosomes:
DNA & proteins
• Nucleolus
Bodies where
ribosomes are made
Mitochondria
Mitochondria: Provides energy to cell by
converting sugars into chemical energy
(respiration)
• “The powerhouse of the cell”
Parts of the Mitochondria
Chloroplasts
• Chloroplasts: Site for photosynthesis.
• Produce sugars from carbon dioxide,
water and sunlight.
Parts of a chloroplast
Chloroplasts
• Contain chlorophyll (makes the plant green)
Vacuole
• Vacuole: Stores a watery solution of sugars,
salts, acids, proteins.
Vacuole
• Makes up to 90% of plant cell volume
• Makes cells turgid
• Has its own membrane, called tonoplast
vacuole
Vacuole contents
• Often acidic content (sap),
it’s what makes lemons and limes taste tart!
Ribosomes
• Ribosomes: are the site for protein synthesis
• Use information contained in DNA to produce
proteins.
• Not membrane bound.
Endoplasmic Reticulum (ER)
• Endoplasmic Reticulum (ER): a network of
folded membranes throughout the
cytoplasm
Endoplasmic Reticulum (ER)
Smooth ER: lacks ribosomes, used for
packaging and transport of proteins, also to
make lipids
Rough ER : has ribosomes for protein
synthesis
Golgi apparatus
• Golgi apparatus:
• A stack of flattened, hollow, membranous
sacs
• Modifies proteins, lipids from the ER.
• Packages these materials in vessicles to the
plasma membrane.
• “UPS of the cell”
Ribosomes, ER & Golgi in action:
The plant cell is like a “Chemical Factory”
Endosymbiont Theory
How did eukaryotic organisms evolve?
How did chloroplasts and mitochondria evolve?
Chloroplasts and mitochondria:
• Same size as bacteria
• Have their own DNA
• Divide similarly
Cyanobacteria Chloroplasts
Endosymbiont Theory (p.26, box 2.2)
• Chloroplasts and Mitochondria are descendants
of once free-living prokaryotes that were
engulfed by larger cells…
establishing a symbiotic (mutually beneficial)
relationship.
THANKS!
Next week: Plant anatomy &
physiology…
Have a great weekend!