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Life Science Handout

Chapters 1 & 2

Chapter 1: Cell Structure & Function

I. Animal Cell:

II. Plant Cells

I) Atoms, Elements, Compounds and Mixtures

A) Definitions

1) Atom: The basic building block of matter, unable to be subdivided by ordinary chemical means.

2) Element: Substance composed entirely of one type of atom. About 100 different atoms are known

to exist.

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3) Compound: Two or more elements combined chemically (Ionic or covalent) in a definite

proportion forming a Molecule.

4) Mixture: Substances that are mixed physically- not chemically- where proportions are not fixed.

B) Atomic Structure

1) Nucleus: The central part of the atom surrounded by an electron cloud. Composed of protons and

neutrons.

2) Proton: About the same mass as a neutron. Each proton has an electrical charge of +1.

3) Neutron: About the same mass as a proton. Each neutron has a neutral electrical charge.

4) Electron: Found in shell clouds surrounding the nucleus. Has about 1/2000th

the mass of a proton

and has a –1 electrical charge.

C) Periodic Table

1) Elemental Symbols: need to knows:

(a) Hydrogen H 1 (f) Sodium Na 11 (k) sulfur S 16

(b) Helium He 2 (g) Chlorine Cl 17 (l) phosphorus P 15

(c) Carbon C 6 (h) Potassium K 19

(d) Nitrogen N 7 (i) Calcium Ca 20

(e) Oxygen O 8 (j) Iron Fe 26

2) Atomic Number: Number of protons found in the nucleus of the atom

3) Atomic Mass: The sum of # of protons and # of neutrons found in the atom. Also the weight in

grams of one mole of the substance.

4) Isotope: Varieties of an element that differ only in the # of neutrons found in the nucleus of the

atom.

5) Mole: 6.02 x 1023

atoms of the substance: One reactive unit. One mole of a substance weighs its

atomic mass in grams. I.e. one mole of carbon weighs 12.0111 grams.

D) Chemical Bonding and Chemical Reactions

1) Electron Energy Levels: Each level will hold 2 electrons

(a) 1S: 2 electrons

(b) 2S: 2 electrons

(c) 2P1: 2 electrons

(d) 2P2: 2 electrons

(e) 2P3: 2 electrons

(f) 3S: 2 electrons

2) Chemical reactions take place with the exchange of electrons found in the outer electron energy

levels of the reactant chemicals. Chemical reactions do not involve the nucleus of the atoms.

3) Ionic Bonds: Sodium Chloride: NaCl

(a) Sodium has only one electron in its outer layer. It gives this electron up to Chlorine because

chlorine needs only one more electron to fill its outer energy level. Chlorine takes control of

this electron and now has an extra electron and becomes a –1 electrical charge. The Sodium

gives the electron up to Chlorine and now has a +1 electrical charge. These are called ions of

the element.

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4) Covalent Bonds: Sharing electrons: water: H2O

(a) Oxygen needs two electrons to fill its outer shell. Hydrogen needs 1 electron to fill its shell.

By sharing its electron with oxygen, the two hydrogens have their shell full and are now

stable. The Oxygen will use the electron from each of the hydrogens to fill its outer shell and

become stable. The three outer energy levels of the two hydrogen and one oxygen atom are

now full and the molecule becomes very stable.

5) Chemical Formulas: The Elements and proportions found in a molecule or compound.

(a) Each element is represented by its chemical symbol and the # of atoms in subscript:

(i) Water: H2O: 2 hydrogen and 1oxygen

(ii) Table salt: Sodium Chloride: NaCl: 1 Sodium and 1 Chlorine

(iii) Glucose: C6H12O6: 6 carbon, 12 hydrogen and 6 oxygen

(b) Chemical Reactions can be written as a formula with reactants on the left and products on

the right side of the arrow:

(i) Reactant + Reactant � Product

(ii) 6CO2 + 6H2O � C6H12O6 + 6O2

(iii) Law of the Conservation of Mass requires that the same # of atoms found on the left

side must also equal the same # of atoms on the right side. In this case there are a total of

6 carbons, 18 oxygens and 12 hydrogens on each side of the equatio

II) Organic verses Inorganic

1) Organic Compounds: Most compounds that contain CARBON are considered to be organic.

Exception would be CO2, carbon dioxide & CO carbon monoxide.

2) Inorganic Compounds are those that do not contain carbon.

3) The most important groups of organic compounds found in living organisms are: Carbohydrates,

Proteins, Lipids and Nucleic Acids

(a) Carbohydrates: and energy rich made of simple sugars & contain: Carbon, Hydrogen and

Oxygen. Examples of foods include glucose, sugars, starch, pastas, rice and breads.

(b) Proteins: Large organic molecules made of carbon, nitrogen, oxygen, hydrogen and

sometimes sulfur. Examples include Meat, eggs, fish, Cell membrane, enzymes and hormones

(i) Protein molecules are made up of smaller molecules called amino acids. There are 20

different amino acids and they are used to make thousands of different proteins

(ii) Enzymes: a special type of protein that speeds up chemical reactions inside the cell.

W/out enzymes most life sustaining chemical reactions would not be able to take place.

(c) Lipids: Energy rich organic molecule containing carbon, hydrogen and oxygen. Broken into

fatty acids & gylcerides Contain more energy potential than carbohydrates. Example:

Cholesterol

(d) Nucleic Acids: Very Large organic molecules that contain: carbon, nitrogen, oxygen,

hydrogen and phosphorus. Made up of nucleotides. Examples: DNA, mRNA, tRNA, rRNA

(i) DNA: Deoxyribonucleic Acid

(ii) RNA: Ribonucleic Acid

III)

IV) Movement of Substance into and out of the cell

A) Passive Transport: movement of substances w/out added energy

a. Diffusion: Movement of a substance from a higher concentration to that of a lower

concentration.

b. Osmosis: diffusion of water molecules from a high concentration to a lower concentration

B) Active transport: requires energy to be expended by the cell. Often moving substances from low

concentration to high concentration. Often uses “Transport Proteins” which grab molecules

outside the cell and pull them inside the cell: example insulin requires a transport protein to enter

the cell.

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V. Chapter 2

A. Photosynthesis: Light & Dark reactions

1. 6CO2 + 6H2O ���� C6H12O6 + 6O2 2. Light striking the green leaves of a plant absorb the visible spectrum and reflects back

(doesn’t use) the green part of the spectrum

a. Leaf is green due to the presence of Chloroplast

1. Chloroplast is made up of

a. The lamella, “Stacks of Coins” like structures called Grana

b. Space between the grana is called the stroma

2. Light Reaction takes place in the Grana:

a. converts light energy into short term high chemical energy molecules

b. H2O ���� O2

c. ADP (low energy)���� ATP (high energy)

d. NADP (low energy)���� NADPH (high energy)

3. Dark Reaction takes place in the Stroma:

a. converts short term high energy chemical energy into long term

b. CO2 ���� C6H12O6 (glucose)

c. ATP (high energy) ����ADP (low energy)

d. NADPH (high energy) ���� NADP (low energy)

B. Respiration

1. Cellular Respiration – cells breakdown glucose and release their stored energy for

use in the cell

2. Two part process

a. In the cytoplasm: Glucose breaks down into smaller molecules without the

use of Oxygen & releases some energy.

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b. In the mitochondria: the small molecules utilize oxygen and releases large

quantities of energy and converts these small molecules into water.

3. Fermentation: Respiration in the absence of Oxygen – 2 types

a. Alcohol fermentation – yeast, a fungi converts sugars into alcohol &

releases energy

b. Lactic Acid Fermentation – muscles without enough Oxygen convert sugars

into lactic acid to release the needed energy for contractions.

C. Mitosis – Cell Division – The Cell Cycle – IPMAT & Cytokinesis

A. Interphase

a. Between cell divisions

b. Cell grows and develops

c. DNA Replication (Chromosome doubles, held together at centromere)

d. Organelle synthesis

B. Prophase

a. Chromosomes condense and coil

b. Centrioles (in animal cells) move toward poles w/ spindle fibers (Fishing Line)

attached to centromeres

c. Longest of the phases (except for Interphase)

d. Nucleolus and nuclear membrane dissolve

C. Metaphase

a. Shortest of the phases

b. Duplicated chromosomes line up at the equator

D. Anaphase

a. Centromeres splits allowing Chromotids to be pulled towards the poles

b. Phase ends when chromosomes reach the poles and stop moving

E. Telophase

a. Chromosomes uncoil and becomes “thready” chromatin material again

b. New nuclear membrane and nucleolus develop

F. Cytokinesis

a. “Water balloon” pinches off the cell forming two separate daughter cells

b. Cell plate separates cells in plants

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II. DNA

A. Carries all of the genetic information needed to carry on all of the cells day-to-day requirements

B. During Mitosis DNA is replicated into two identical strands then distributed into each daughter

cell.

C. DNA is found on chromosomes which are located in the nucleus.

D. One chromosome consists of two chromotids held together by a centromere.

a. Each upper & lower half of a chromotid is a telomere

A. Structure

a. DNA is made up of segments called nucleotides.

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b. Nucleotide made up of Phosphate group, Deoxyribose Sugar and Nitrogenous base

i. Nitrogenous bases:

1. A = Adenine,

2. G= Guanine,

3. T= Thymine

4. C= Cytosine

ii. A only binds w/ T

iii. G only binds w/C

iv. Bases (ladder rungs) held together by hydrogen bonds

c. Double helix – Twisted ladder, Structure identified by Watson and Crick

B. Replication

a. Occurs when enzyme “unzips” DNA

b. Millions of new nucleotides floating thru the nucleus

c. More enzymes brings nucleotides to attach them correctly to the exposed strands of DNA

d. Creates two identical strands of original DNA molecule

e.