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Joy of Science
Experience the evolution of the Universe,
Earth and Life
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Review
Introduction
Main contents
Group discussions
Unless otherwise noted, pictures are taken from wikipedia.org
Review 1
— 
Organic molecules always contain
1. water
2. oxygen
3. carbon
4. nitrogen
5. phosphorus
Review 1
— 
Organic molecules always contain
1. water
2. oxygen
3. carbon
4. nitrogen
5. phosphorus
Review 2
— 
The building blocks of proteins are
1. carboxyl groups
2. enzymes
3. monosaccharides
4. disaccharides
5. amino acids
Review 2
— 
The building blocks of proteins are
1. carboxyl groups
2. enzymes
3. monosaccharides
4. disaccharides
5. amino acids
Review 3
— 
A substance that controls the rate of a chemical reaction in living
organisms is
1. an amino acid
2. an enzyme
3. a monosaccharide
4. a carboxyl group
5. carbon
Review 3
— 
A substance that controls the rate of a chemical reaction in living
organisms is
1. an amino acid
2. an enzyme
3. a monosaccharide
4. a carboxyl group
5. carbon
Review 4
— 
Carbohydrates consist of
1. C, H, O
2. C, N, H
3. N, H, O
4. Ca, C, N
5. P, C, N
Review 4
— 
Carbohydrates consist of
1. C, H, O
2. C, N, H
3. N, H, O
4. Ca, C, N
5. P, C, N
Cells and Inheritance
cells: complex chemical systems with the ability
to duplicate themselves
Today’s Keywords
cell, cell membrane, nucleus, organelle,
chloroplasts, mitochondria, metabolism
Contents of today’s lecture
1. Introduction
2. Cell organelles and their functions
- Cell membranes
- The nucleus
- Energy organelles: Chloroplasts and Mitochondria
- Cytoskeleton
3. Metabolism
4. Cell division
1. Introduction
1. Introduction
— 
What makes living things different from just collection of atoms?
“A living thing must take in matter and energy and reproduce itself.”
— 
A cell is the smallest identifiable unit of carrying on the statement above
— 
An enormous number of different kinds of cells in nature with different
sizes and shapes
— 
Different shapes reflect different functions that the cells perform
— 
To fulfill their functions, cells constantly require raw materials and energy
— 
The cell theory
1. All living things are composed of cells
2. The cell is the fundamental unit of life
3. All cells arise from previous cells
1. Introduction
Cells - The name from “cork”s “small room” structure
The structure of cells in
micrograph of cork, taken from
the bark of cork oak tree
Cells stained for keratin
(red) and DNA (green)
2. Cell organelles and their functions
1. 
2. 
3. 
4. 
Cell membranes
The nucleus
Energy organelles: Chloroplasts and Mitochondria
Cytoskeleton
2. Cell organelles and their functions
— 
— 
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Cell membranes
The nucleus
Energy organelles: Chloroplasts and Mitochondria
Cytoskeleton
Plant cell
2. Cell organelles and their functions
— 
— 
— 
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Cell membranes
The nucleus
Energy organelles: Chloroplasts and Mitochondria
Cytoskeleton
Animal cell
— 
Cell membranes
2. Cell organelles and functions
: separate the interior of all cells from the outside environment
— 
Cell membranes
: separate
2. Cell organelles and functions
the interior of all cells from the outside environment
- The basic structure of cell membranes: a flexible double layer of
elongated lipids
- Materials are transported across cell membranes in many ways,
depending receptors which are large protein molecular structures in
membranes
- Each receptor molecule has a specific geometrical shape, and binds to a
specific type of molecule in the environment
— 
Cell membranes (cont’d)
2. Cell organelles and functions
The action of receptors in a cell:
1. A receptor recognize a particular molecule and they attract each other
2. The receptor binds to the particle and holds it
3. The cell membrane deforms and enclose the particle in its own
wrapping
4. The container, called a vesicle, moves the particle around inside the cell
5. A similar process works in reverse when molecules are moved out
from inside
— 
Receptor
(protein)
Cell membranes
cell
2. Cell organelles and functions
— 
The cell Nucleus
- The most prominent and important interior structure in most cells
- Contains the cell’s DNA, which gives the instruction of daily
operation of the cell and the mechanism of reproduction of the cell
itself (will be discussed next week)
- Prokaryotes (“before the nucleus”): all cells without a nucleus,
but with a nucleoid which is a tight coil containing DNA
Eukaryotes (“true nucleus”): all cells with a nucleus including
advanced single-celled organisms as well as multicellular organisms
- The nucleus has a double-membrane!: it once may have been an
independent cell !!!
2. Cell organelles and functions
— 
The cell Nucleus
— 
Interior structures with a double membranes in cells suggest
that individual cells in complex organisms may be more like colonies
of smaller cells, and provide a good feature of the evolution of higher
life-forms
Independent
free-living
prokaryotic
cells
— 
The cell Nucleus
cell
Cell Nucleus - two types of cells
A bacterium
Prokaryote
Meaning: before nucleus
Meaning:
Nucleus-like
Nucleus
Eukaryote
Meaning: true nucleus
2. Cell organelles and functions Energy organelles : Chloroplasts, Mitochondria
(* organelle: any specialized inner structure in eukaryotic cells)
— 
Chloroplasts
- Main energy transformation organelle in plant cells
- Green color because of chlorophyll pigment
- Absorb energy from sunlight (energy source of plants) and produce
energy-rich sugar molecules such as glucose through photosynthesis
- They have a double cell membrane and their own DNA
— 
Chloroplasts
2. Cell organelles and functions - Main energy transformation organelle in plant cells
- Green color because of chlorophyll pigment
- Absorb energy from sunlight (energy source of plants) and produce
energy-rich sugar molecules such as glucose through photosynthesis
- They have a double cell membrane and their own DNA
Plant cell
2. Cell organelles and functions — 
Mitochondria
- Sausage-shaped organelles
- Called "cellular power plants" because they generate ATP which is a
molecule that provides energy for countless chemical reactions, using
energy from sugar glucose with oxygen
- They have a double cell membrane and their own DNA
Plant cell
Animal cell
mitochondrion
— 
Cytoskeleton
2. Cell organelles and functions - A cellular “skeleton” contained within the cytoplasm (fluid) and is
made of protein
- Gives the cell its shape and keeps things anchored in place
- Plays important roles in both intracellular transport (the movement
of vesicles and organelles, for example) and cellular division
Eukaryotic cytoskeleton consists of 3 filaments,
Microfilaments (actin filaments) in red
Intermediate filaments not stained
Microtubules in green
Nuclei are stained with blue in the picture
3. Metabolism
3. Metabolism: Energy and Life
(The cell’s process of deriving energy from its surroundings)
1. 
2. 
3. 
4. 
Cell’s energy currency: a few molecules store and distribute
energy in all living things
Photosynthesis: energy in the form of sunlight plus carbon
dioxide plus water react to produce carbohydrate plus oxygen
in chloroplasts
Glycolysis: the first step in energy generation in the cell
Respiration, Fermentation: two separate and distinct
energy generating ways after glycolysis
— 
3. Metabolism
Cell’s energy currency
- A few molecules store and distribute energy in all living things
- ATP (adenosine triphosphate): the most common energy carrier,
consisting of 3 phosphate groups, a sugar (ribose), and a base
Base
Phosphate groups
ATP
sugar
— 
Cell’s energy currency (cont’d)
Metabolism
- A few molecules store and distribute energy in all living things
- ATP (adenosine triphosphate): the most common energy carrier,
consisting of 3 phosphate groups, a sugar (ribose), and a base
- The Process of chemical reactions to produce and distribute energy in the
form of ATP
1. In a place in a cell, e.g. mitochondrion, chemical reactions produce
energy and store the energy in the form of ATP molecules
2. ATP molecules move out of the place to a new place where
energy is needed
3. An ATP molecule attaches to part of the cell’s chemical machinery,
a phosphate group is removed, and the stored energy becomes to
derive new chemical reactions
ATP à ADP (diphosphate)+ PO4 (a phosphate group) + energy
— 
Metabolism
Photosynthesis
- Energy in the form of sunlight plus carbon dioxide plus water react to
produce carbohydrate (such as glucose) plus oxygen in chloroplasts
(chlorophylls)
energy(sunlight) + CO2 + H2O à carbohydrates + O2
Taken from http://hubpages.com/
Metabolism
— 
Glycolysis
- The primary source of energy for living things comes from oxidation of
carbohydrates such as glucose (this sort of reaction is called Respiration)
- Glycolysis: the first step in energy generation in mitochondria in cells
(meaning of “splitting glucose”)
- Glucose splits to two molecules of pyruvic acid plus smaller energy-rich
molecules
glucose à 2 pyruvic acid + energy
(stored in 2 ATP and 2 NADH;
* 1 NADH à 2 or 3 ATP)
- The total number of ATP molecules from one molecule of glucose is 6-8
— 
Process of Glycolysis
3. Metabolism
Energy added
Energy added
Energy released
Energy released
X2
Energy released
3. Metabolism
— 
Fermentation
- A way to keep glycolysis going in the absence of oxygen
- Energy generating process without oxygen - anaerobic
- A single-celled yeast produce ethanol
- In cells of animals, fermentation reactions produce energy and lactic
acid which accumulated in muscles later (and then makes bodies feel
tiredness)
è Cells evolved fermentation reactions first then developed ability to
burn oxygen
— 
Final stage of Respiration
3. Metabolism
- In oxygen available cells, molecules of pyruvic acid enter a complex
series of chemical reactions, called Krebs cycle
- Energy generating process with oxygen – aerobic
- Carbohydrates plus oxygen react to produce energy plus carbon
dioxide plus water
carbohydrates + O2 à energy + CO2 + H2O
(in the form of ATP and other small molecules)
- The reverse of photosynthesis
- With oxygen, the total number of ultimately produced ATP molecules
from a glucose is 36-38! è necessity of oxygen for evolution of
complex life-forms !!!
4. Cell Division
4. Cell division
: cells divide and reproduce themselves by two separate
processes
1. 
2. 
Mitosis 体細胞分裂
Meiosis 減数分裂 4. Cell Division
4. Cell division
: cells divide and reproduce themselves by two separate
processes
1. 
2. 
Mitosis 体細胞分裂
Meiosis 減数分裂
The information of reproduction is in DNA which is
contained in an organelle chromosome in eukaryote cells
(chromosomes come in pairs, the number of pairs depends
on species: humans-23 pairs, dogs-39pairs, mosquitos-3pairs,
etc.)
4. Cell division
— 
Mitosis 体細胞分裂
- The process of a single cell splitting: the majority of cell divisions
- Reproduction of individual cells but not involved in sexual
reproduction only in a eukaryotic cell
— 
Mitosis 体細胞分裂
4. Cell division
- The process of mitosis
1. Copying of the chromosomes
2. Nuclear membrane dissolves and a series of fibers
(spindle fibers) develop
3. The matched chromosomes pairs are pulled apart
and migrate to opposite ends of the cell
4. Nuclear membrane reforms and the cell splits down
the middle
è Result: two daughter cells
è Each cell in the result carries a set of chromosomes that are
identical to the original
4. Cell division
— 
Meiosis 減数分裂
- Specialized cell division: taking place in a few cells of reproducing
sexually
- The process of production of sperms or eggs (ovum)
- Each daughter cell in the result has its own unique new combination
of genetic material
— 
Meiosis 減数分裂 (cont’d)
4. Cell division
- The process of meiosis has two big steps
1. First step
a. Coping chromosomes in the cell
b. Copied chromosomes in “X-shape” cross over each other and
exchange short lengths of genetic materials
2. Second step
a. Four X-shaped pairs of chromosomes segregate along spindle fibers
and then the cell divides in the middle à two daughter cells have
two pairs of X-shaped chromosomes
b. Each cell pulled by spindle fibers splits again, then the result has all
four daughter cells with half the normal complement of the original
cell
Next lecture is on,
DNA: Chapter 16
www.sci.hokudai.ac.jp/~epark/ekpark_e.html