Joy of Science Experience the evolution of the Universe, Earth and Life

Joy of Science Experience the evolution of the Universe, Earth and Life 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 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 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. Cell membranes 2. The nucleus 3. Energy organelles: Chloroplasts and Mitochondria 4. Cytoskeleton

2. Cell organelles and their functions Cell membranes The nucleus Energy organelles: Chloroplasts and Mitochondria Cytoskeleton Plant cell

2. Cell organelles and their functions 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 2. Cell organelles and functions : separate 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

Cell membranes cell Receptor (protein)

The cell Nucleus 2. Cell organelles and functions - 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

Energy organelles : Chloroplasts, Mitochondria (* organelle: any specialized inner structure in eukaryotic cells) 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

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

Mitochondria 2. Cell organelles and functions - 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. Cell s energy currency: a few molecules store and distribute energy in all living things 2. Photosynthesis: energy in the form of sunlight plus carbon dioxide plus water react to produce carbohydrate plus oxygen in chloroplasts 3. Glycolysis: the first step in energy generation in the cell 4. Respiration, Fermentation: two separate and distinct energy generating ways after glycolysis

Cell s energy currency 3. 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 Phosphate groups ATP Base 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)+ PO 4 (a phosphate group) + energy

Photosynthesis Metabolism - 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) + CO 2 + H 2 O à carbohydrates + O 2 Taken from http://hubpages.com/

Glycolysis Metabolism - 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 X 2 Energy released

Fermentation 3. Metabolism - 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 + O 2 à energy + CO 2 + H 2 O (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 : cells divide and reproduce themselves by two separate processes 1. Mitosis 2. Meiosis 4. Cell division

4. Cell Division : cells divide and reproduce themselves by two separate processes 1. Mitosis 2. Meiosis 4. Cell division 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 - 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 - 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

4. Cell division Meiosis - 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

4. Cell division Meiosis (cont d) - 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