Parts of an animal cell ( click on image to zoom in)

Organelles in an Animal Cell:

Nucleus:"control center", membrane-enclosed organelle, contains DNA molecules
Nuclear Pore: opening in the nuclear membrane for mRNA to go into the cytoplasm
Chromatin: complex combination of DNA, RNA and protein that makes up chromosomes
Nucleolus: partially synthesizes and assembles ribosomes
Nuclear envelope: membrane surrounding nucleus, endoplasmic reticulum is attached
Ribosomes:manufacture proteins (assembly of amino acids into polypeptide chains)
Plasma (cell) membrane: controls what goes into (nutrients) and out (wastes) of the cell
Mitochondria:"cellular power plants", generate cell's supply of ATP
Peroxisome: contains enzymes that rid the cell of toxic peroxides.
Cytoskeleton: "skeleton" structure that maintains cell shape, protects the cell, enables motion
Free ribosomes:not attached to the endoplasmic reticulum
Smooth endoplasmic reticulum:synthesis of lipids, steroids, metabolism of carbohydrates
Rough endoplasmic reticulum: joined to the outer layer of the nuclear envelope, ribosomes attached
Secretory vesicle:enclosed vacuole uses to move proteins around or out of the cell
Cytoplasm:jelly-like substance, site where most cellular activities (reactions) occur
Centrioles:organization of the mitotic spindle and in the completion of cytokinesis
Lysosome:contains digestive enzymes to breakdown food particles, or engulfed bacteria.
Golgi apparatus (complex): process and package proteins and lipids, for transport and secretion.
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Parts of a plant cell (click on the image to zoom in)

Organelles in a Plant Cell:

* Cell membrane: controls what goes into (nutrients) and out (wastes) of the cell
* Cell wall: supports and protects the cell
* Nuclear membrane: barrier between the nucleus and the cytoplasm
* Plasmodesma: channels between cell walls for transport and cell-cell communication
* Vacuole: stores water, food and wastes
* Plastids: manufacture / storage of important chemical compounds
* Chloroplast: green plastid, contains chlorophyll needed in photosynthesis
* Leucoplast: another plastid, bulk storage of starch, lipid or protein
* Chromoplast: plastids responsible for pigment synthesis and storage
* Golgi Complex: process and package proteins and lipids, for transport and secretion.
* Ribosome: manufacture proteins (assembly of amino acids into polypeptide chains)
* Endoplasmic reticulum:intercellular network, transport of proteins inside / out of cell
* Mitochondrion: "cellular power plants", generate cell's supply of ATP
* Lysosome: contains digestive enzymes to breakdown food particles, or engulfed bacteria.
* Cytoplasm:jelly-like substance, site where most cellular activities (reactions) occur
* Nucleus: "control center", membrane-enclosed organelle, contains DNA molecules
* DNA: Deoxyribonucleic acid (DNA) contains the long-term genetic instructions
* Chromatin: complex combination of DNA, RNA and protein that makes up chromosomes
* RNA: RNA is transcribed from DNA to create the instructions (mRNA) for proteins
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Prokaryotic cell parts and functions

This is a prokaryotic cell. Note the parts and their functions:

Ribosomes: synthesize proteins
Plasmids: extracellular DNA transmitted through conjugation, ex: creates antibiotic resistance
Flagella: used for motility (movement)
Cell wall: supports and protects
Plasma membrane: controls what enters (nutirents) and leaves (wastes) the cell
Chromosome: contains DNA, instructions for the cell
Cytoplasm: jellylike, contains nutrients and chemicals needed for reactions
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Light dependent reaction in photosynthesis

The light dependent reaction (light reaction) of photosynthesis:

Light energy and the synthesis of ATP, photolysis, oxygen and hydrogen.

(a) Light is absorbed by chlorophyll molecules (green) on membranes inside the chloroplast. This is the light trapping stage in which photons of light are absorbed by the chlorophyll and turned into chemical energy (electrons).

(b) The chemical energy (electrons) is trapped in making ATP.

(c) Photolysis: water used in photosynthesis is split which provides hydrogen for the formation of organic molecules (C₆H₁₂O₆) in the light independent reaction. Oxygen gas is given off.

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Overview of Photosynthesis

Photosynthesis:

Key concepts:

1. Photosynthesis involves the conversion of light energy into chemical energy.

2. White light from the Sun is composed of a range of wavelengths (colors).

3. Chlorophyll is the main photosynthetic pigment and absorbs red and blue wavelengths most efficiently. Chlorophyll reflects green wavelength. This is why many plants are "green" colored.

4. The light energy is used to produce ATP, and to split water molecules (photolysis) to form oxygen and hydrogen.

5. The ATP and hydrogen (derived from the photolysis of water) are used to fix carbon dioxide to make organic molecules.

6.The rate of photosynthesis can be measured directly by the production of oxygen or the uptake of carbon dioxide, or indirectly by the increase in biomass or O2 production.

7. The rate of photosynthesis is effected by the temperature, light intensity and carbon dioxide concentration.

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Human Cellular Respiration

Summary of Human cellular respiration:

(a) Glucose transported to the cell diffuses into the cytoplasm. Glucose is the initial substrate for respiration.

(b) Glycolysis in which glucose with six carbons is broken down into two pyruvate each with 3 carbons. This yields a small amount of ATP.

(c) Anaerobic respiration in which lactic acid is produced, oxidation from glucose yields a small amount of ATP. Remember that anaerobic respiration will occur at the same time as aerobic respiration to provided more energy.

(d) Aerobic respiration in which pyruvate is broken down, oxidised, further in the mitochondria where a lot of ATP is produced.

(e) Oxygen is required for step (d) to be completed. This is transported to the cell on the hemoglobin found inside red blood cells.

(f) carbon dioxide is produced as waste from aerobic respiration it diffuses into the blood and is transported to the lungs where it is excreted in exhaled air.

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Aerobic Respiration:

Aerobic cell respiration produces a large yield of ATP.

Aerobic respiration:
in the presence of oxygen, the pyruvate formed during glycolysis can be used to make as much as 36 more ATP thus, aerobic respiration is the main source of ATP for cellular functions in eukaryotes.

Pyruvate from glycolysis diffuses from the cytosol(cytoplasm) into the mitochondrial matrix.In the mitochondria a series of reactions (link reaction, Krebs cycle or cytric acid cycle, electron transport system, oxidative phosphorylation) oxidize pyruvate to produce ATP. The by-products of oxidation include carbon dioxide and water.

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Anaerobic Cellular Respiration:

Anaerobic respiration or fermentation:

1. In the absence of oxygen, the pyruvate formed during glycolysis (the break down of glucose) can’t be used to make more ATP; thus, glycolysis is the only source of ATP for cellular functions since glycolysis is the only source of ATP. it must be kept going.

2. NAD occurs in many living cells and functions as an electron acceptor. Oxidation is loss of electrons and reduction is gain of electrons. NAD is used alternately with NADH in metabolic reactions to gain or lose electrons. Glycolysis reduces NAD+ to NADH + H+, depleting the supply of NAD and without NAD+, glycolysis will come to a halt. Therefore, NADH + H+ must be oxidized back to NAD+. Fermentation allows for the oxidation of NADH + H+ back to NAD+, by reducing pyruvate to either lactate (in animals lactic acid causes sore muscles) or ethanol (yeast produce alcohol when fermenting beer or wine and give off CO2).

Anaerobic respiration in animals:

Anaerobic respiration in yeast:

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Cellular Respiration Overview:

Cellular Respiration

Key Concepts:

1. Cellular respiration is the controlled release of energy in the form of ATP from organic compounds in cells.

2. In cell respiration, glucose in the cytoplasm is broken down into pyruvate, with a small yield of ATP.

3. Cellular respiration can occur without oxygen present (anaerobic respiration) or with oxygen present (aerobic respiration)

4. During anaerobic cell respiration, pyruvate can be converted in the cytoplasm into lactate, or ethanol and carbon dioxide, with no further yield of ATP.

5. During aerobic cell respiration, pyruvate can be broken down in the mitochondrion into carbon dioxide and water with a large yield of ATP.
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Macromolecules

Carbohydrates, Lipids and Proteins

Distinguish between organic and inorganic compounds: compounds containing carbon that are found in living organisms are regarded as organic (with some exceptions such as CO2); all other compounds are regarded as inorganic

Types of macromolecules:

Amino acids are the building block to make proteins. Proteins make enzymes which catalyse (speed up) chemical reactions. Examples are aklanine, leucine and glycine. Proteins also make up cell parts. Structurally, they look this this (but the R side group group can vary):

Sugars are the building blocks of carbohydrates, the chief energy source for living things. Carbohydrates may be made of one sugar (monosaccharide such as glucose produced in photosynthesis; two sugars or a disaccharide such as sucrose the common "grocery store" sugar; or many sugar units called polysaccharides such as starch or glycogen which both store energy for release later during respiration. The structure of glucose is shown below.

Lipids such as fats and oils are used for long-term energy storage, structural framework of cellular membranes; act as thermal insulation
(example: fat layer for a seal) and make up hormones (messenger molecules).Lip[ids are primarily made of fatty acids which are shown below.

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Water Properties and H-Bonding

Properties of Water in Living Organisms

thermal properties: hydrogen bonds between polar water molecules cause water to resist change such as boiling or freezing, thus, water produces a stable environment for aquatic organisms


cohesion: hydrogen bonds between polar water molecules cause them to cohere (stick together) allowing for transpiration in plants moving water against gravity, surface tension between water molecules allowing for animals such as water striders to walk over the surface of ponds

solvent properties:the polarity of water attracts, or dissolves, any other polar or charged particles by forming hydrogen bonds with them proteins, glucose, or ions, such as sodium or calcium are all soluble


medium for metabolic reactions: cytoplasm is primarily water, providing a polar medium in which other polar or charged molecules are dissolved for metabolic reactions

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Common elements in living things

Common Elements in Living things

All living things are composed of matter that contains the same core elements of carbon, hydrogen, oxygen and nitrogen. These elements are combined along with a few other less common elements to give the 'biological molecules' of carbohydrates, proteins and lipids and DNA.

A variety of other elements are needed by living organisms including :

Sulfur: (S) essential element in variable group of some amino acids (therefore proteins)

Calcium: (Ca) essential element in bones, teeth, shells, nerve function

Phosphorus: (K) essential element in nucleotides, including ATP

Iron: (Fe) essential element in heme group of hemoglobin, oxygen transport molecule

Sodium: (Na) required for nerve impulse transmission
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Cell Differentiation and Emergent Properties

Emergent Properties and Cell Differentiation

Multicellular organisms show emergent properties: emergent properties arise from the interaction of component parts
the whole is greater than the sum of its parts life itself can be viewed as an emergent property. Example would be swarming in bees, an ant colony and the human brain.

Cells in multicellular organisms differentiate to carry out specialized functions by expressing some of their genes but not others.

unicellular organisms must solve all of life’s challenges within the confines of a single cell

multicellular organisms can differentiate into a variety of interdependent cell types each specialized to carry out specific functions thereby achieving a greater efficiency through division of labor within the cells of the organism.

cellular differentiation: achieved through differential gene expression, all cells in an organism have identical DNA but different cell types make different proteins by“turning on” some genes and “turning off” others. For example, a muscle cell will express muscle genes but not those genes which are for nerve cells.
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Surface Area to Volume Ratio

The importance of the surface area to volume ratio limiting cell size

surface area: the rate of exchange of materials into and out of the cell is a function of the surface area.

volume:the metabolism of the cell (the chemical processes occurring within a living cell or organism that are necessary for the maintenance of life) is a function of the volume. Metabolism includes heat production/waste production/resource consumption of a cel.

therefore: as the dimensions of a cell increase, V increases proportionally faster than SA thus, SA/V ratio decreases with cell size setting an upper limit on cell size. Lower relative SA reduces rate of exchange while higher relative V increases metabolic demands thus, rate of exchange can’t meet needs of metabolic demands. The cell (usually) will either divide into two smaller cells or may die.

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Active Transport

Active Transport

Explain the role of protein pumps and ATP in active transport across membranes.

Against the concentration gradient: Moves substance from an area where it is in lower concentration to an area where it is in higher concentration.

Protein pumps: Integral protein pumps embedded within membranes. Specific to molecule transported.

Requires energy: Usually provided by ATP.

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Passive Transport

The Plasma Membrane

Passive Transport across a membrane

Definitions:

Diffusion = the passive movement of particles from a region of higher concentration to a region of lower concentration.


Osmosis = the passive movement of water molecules,
across a partially permeable membrane, from a region of lower solute
concentration to a region of higher solute concentration.

Explain passive transport across membranes in terms of simple diffusion and facilitated diffusion.

Concentration gradient: Molecules can diffuse across membranes from areas of higher to lower concentration by:

Simple diffusion: traveling directly through the membrane if they
are small and uncharged avoiding repulsion by the hydrophobic,
non-polar tails of phospholipids in the middle of the membrane.

Facilitated diffusion: traveling through special transport
proteins, if they match the shape and charge requirements to fit
through the channels provided by the transport proteins.

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Plant vs Animal Cells

Three differences between plant and animal cells

Plant cells

1. cellulose cell walls(gives structure and support to the cell)
2. chloroplasts (captures light energy for photosynthesis)
3. large central vacuole (stores food, water and wastes)

Animal cells

1. no cell walls
2. no chloroplasts
3. lacking or small vacuoles

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Prokaryotic and eukaryotic cells

Compare prokaryotic and eukaryotic cells

Prokaryotic: naked DNA (DNA in cytoplasm), no membrane-bound organelles (no mitochondria, ER, golg), only bacteria


Eukaryotic: true nucleus (DNA enclosed by nuclear membrane), many membrane-bound organelles (mitochondria, ER, golgi) to compartmentalize functions, all cells other than bacteria

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Parts of an Animal Cell

Draw and label an example of an animal cell.

Annotate the diagram with the functions of each named structure.

1. Free ribosomes: -sites of protein synthesis for use within the cytoplasm ribosomes are constructed in the nuclear region called the nucleolus

2. Rough endoplasmic reticulum: flattened membrane sacs, ribosomes synthesize proteins, are packaged in vesicles and transported to Golgi apparatus

3. Lysosomes: vesicles formed by Golgi apparatus , contain enzymes for breaking down ingested food, damaged organelles, or entire cells

4. Golgi apparatus - proteins received from vesicles are processed , carbohydrates added to proteins to form glycoproteins , vesicles of glycoproteins exit Golgi for exocytosis or intracellular use

5. Mitochondria: site of aerobic respiration, producing ATP

6. Nucleus: double membrane bound, containing pores for transport of proteins and ribosomes contains chromosomes, made of DNA + protein site of DNA replication and transcription into RNA
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Functions of Life

Unicellular organisms carry out all the functions of life

Unicellular organisms (Protoctista) evolved some 3-4 Billion (10⁹) years ago. These unicellular life forms remained the dominant life form until the Precambrian period 600million years ago after which multi-cellular life forms proliferated. Other unicellular groups include the prokaryotes (Bacteria) which lack a true nucleus.

1. metabolism: chemical reactions inside the cell, including cell respiration to release energy

2. sensitivity: perceiving and responding to changes in the environment

3. homeostasis: keeping conditions inside the organisms within tolerable limits

4. growth: an irreversible increase in size

5. reproduction: producing offspring either sexually or asexually

6. nutrition: obtaining food, to provide energy and the materials needed for growth

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Cell Theory

Cell theory

1. all living things are made of one or more cells - microscopes allow us to observe that all living things are either unicellular (one cell) or multi-cellular (many cells)

2. the cell is the smallest unit of life - nothing smaller than a cell can survive independently, subcellular structures or organelles cannot survive independently (examples of organelles: nuclei, ER, golgi, chloroplasts, mitochondria)

3. all cells come from pre-existing cells - this seems to imply that life has always existed, which is incompatible with geological evidence about the age of Earth therefore, an exception is made for the origin of life, when cells must have arisen from non-living substance since the conditions of early Earth were anaerobic (without oxygen), they allowed for cells to form from non-living substances. The conditions of present Earth are aerobic (with oxygen), precluding the formation of cells from non-living substance.
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