BASIC BUILDING BLOCKS OF LIFE Building from the atom to the organism

BASIC BUILDING

BLOCKS OF LIFE

Building from the atom to the organism

From smallest to biggest

• Atoms

• Molecules

• Cells

• Tissues

• Organs

• Organisms

What are the basic building block of all things?

• Everything in the universe is made of matter– Anything that occupies space and has mass

• REMIND ME: What is mass ?

Atoms build all things

• Atom – simplest particle of an element that has all the properties of the element.

• Element – found on the periodic table. They cannot be broken down chemically into simpler forms of matter.– Atoms of the same type combine

together to form elements

Important information about the atom

• Atom is made of 3 basic particles:– Protons:

• Positive charged particle in the nucleus• The number of protons determines the element.

This number is known as the atomic number on the periodic table.

– Neutrons:• Neutral charged particle in the nucleus• An element may have different numbers of

neutrons, this is called an isotope.

Electrons

• Electrons– Negatively charged particle orbiting the

nucleus– The area the electrons orbit is called the

orbital– Electrons are responsible for combining

atoms

Combining Atoms

• Things aren’t made of individual elements. They must combine to form more complex structures.

• Molecule – combination of 2 or more atoms

• Compound – combination of 2 or more molecules– Atoms make up elements

– Atoms make up molecules

– Molecules make up compounds

How do atoms and molecules combine?

• Elements and molecules are held together by chemical bonds– Ionic bonds – when atoms are held together by

the attraction of opposite charges, electrons are gained or lost (NaCl)

– Covalent bonds - when atoms are held together by one or more pairs of electrons shared between atoms (H2O)

Atoms want to be stable

• To be stable, all elements want their orbitals full

• To be full, an element must look like a noble gas (last column on the periodic table)– Thus, elements must do 1 of two things:

• Take or lose electrons• Share electrons with another atom

• LET’S LOOK AT SOME EXAMPLES

Let’s examine the periodic table

Try These

• Carbon (C)

• Hydrogen (H)

• Oxygen (O)

• Nitrogen (N)

• Phosphorus (P)

• Sulfur (S)

Let’s put some atoms together

• Each atom can combine with a maximum of 4 other atoms

• This number depends on the number of electrons it gains/loses or has to share

EXAMPLE

• CH4 (the subscript tells you how many

atoms of each type you have)– How many electrons does carbon have to gain

or lose? (1 carbon)– How many electrons does hydrogen have to

gain or lose? (4 hydrogens)

• This is how many places the atom can combine with another atom(s)

EXAMPLE (cont)

• Carbon has 4 spaces

• 4 Hydrogens have 1 space each

• The atom with the most number of spaces is going to go in the middle

How do we put them together?

-C-

H- H- H- H-

Try these with the model kits

• CH4

• H2O

• NH3

• CCl4

Special bond between molecules: HYDROGEN BONDS

• Electrons are usually not shared equally between atoms in a covalent bond

• Some atoms want electrons more than others– EXAMPLE: In water, oxygen wants the

electrons more than hydrogen

• QUESTION: What becomes the charge on the hydrogen and the oxygen?

Polarity

• ANSWER:– Oxygen only has a partial negative charge– Each hydrogen has a partial positive charge

• When a molecule has an uneven sharing of electrons, this is called a polar compound

Water – The molecule of life

• As a result of this polarity in molecules, many molecules in living things create hydrogen bonds.

Properties from Hydrogen bonds

• Because hydrogen bonds help to bond different molecules together, water gets some interesting properties:

• Cohesion – an attractive force that holds molecules together in a single substance– Helps the upward movement of water in a

plants roots to its leaves– Surface tension

Properties from Hydrogen bonds

• Adhesion – attractive force between two different substances– Capillarity – attraction between molecules that

results in the rise of the surface of a liquid when in contact with a solid

• EXAMPLE: allows water to rise up side of roots in plants

Solutions and solubility• Most things in life occur in water or are made of

water.

• Solution – mixture in which one or more substances is dissolved evenly in another substance– Solute – substance dissolved in a

solvent– Solvent - the substance in which a

solute is dissolven

Solutions in water

• In water, all solutions are known as AQUEOUS SOLUTIONS

Acids and bases (always in aqueous solutions)

• Water is able to split apart into two ions

H2O H+ + OH-

• Acid solutions have a greater number of hydrogen ions (H+)

• Base solutions have a greater number of hydroxide ions (OH-)– Also referred to as alkaline

Acids and bases

• Living things need to live in a specific range of acid or base to be healthy

– This is why acid rain kills so many fish in lakes and streams

• pH scale measures relative concentrations of H+ ions and OH- ions

Biological Molecules

• Organic Compounds– CARBOHYDRATES– PROTEINS– LIPIDS– NUCLEIC ACIDS

Carbon bonding

• Organic compounds – compounds made primarily of carbon

• Most living organisms are made up of organic compounds

• Why do you think that so many molecules use carbon?

Functional groups – TURN TO PAGE 52

• ANSWER: Carbon has 4 bonding sites giving it a lot of versatility.

• Functional groups influence the characteristic of molecules as they go through chemical reactions:– Hydroxyl– Carboxyl– Amino– Phosphate

Carbohydrates

• Carbohydrates are organic molecules that are composed of carbon, hydrogen and oxygen– Monosaccharide – a simple sugar. These are the

building blocks for more complex carbohydrates (glucose, fructose, galactose)

– Disaccharide – sugar made of 2 monosaccharides (sucrose)

– Polysaccharide – a complex sugar made up of three or more monosaccharides (starch)

Carbohydrates – TURN TO PAGE 53 AND 55

• Notice the pictures of some example carbohydrates on pg. 55 (Figure 3-6)– These are the monosaccharides

• Disaccharides are formed as seen on pg. 53 (Figure 3-4)– Condensation reaction : combines two

monosaccharides to form a disaccharide and produces water

– Hydrolysis : the opposite of a condensation reaction

Carbohydrates

• Carbohydrates serve a couple of purposes:

– Source of energy

• Glucose is the main source of energy for cells

– Structural material in the cell

• Cellulose is a polysaccharide that give strength and rigidity to plant cells (makes up about 50 percent of wood)

Proteins

• Proteins are organic molecules composed mostly of carbon, hydrogen, oxygen and nitrogen

• A series of protein monomers are linked together to form an amino acid– There are a total of 20 amino acids

– Amino acids are held together by peptide bonds

• Long chains of amino acids are often called a polypeptide

Proteins – TURN TO PAGE 56 AND 57

• Amino acids are made of a central carbon with different groups covalently bonded around it (p. 56 Figure 3-7)

– Carboxyl group

– Amino group

– Hydrogen

– R group (different for every amino acid)

• Peptide bonds are formed and broken apart like carbohydrates (p. 57 Figure 3-8)

• Polypeptide: very long chains of amino acids

ENZYMES

• Enzymes : special type of protein that is used to facilitate many biological reactions (also known as a biological catalyst)

• Enzymes act like a lock and key (only one type of substrate can fit in the enzyme’s active site)– Substrate: substance being catalyzed– Active site: where the substrate fits into the enzyme

Lipids – TURN TO PAGE 59

• Lipid: Organic molecule made mostly of carbon and hydrogen

• IMPORTANT NOTE: Lipids are nonpolar (do not dissolve in water)– Fatty acid: made of a long carbon chain with a

carboxyl group at one end• The long carbon chain is hydrophobic (another

word for does not dissolve in water)• The carboxyl group is hydrophilic (dissolves in

water)

Lipids

• Lipids important to living things– Triglycerides: composed of 3 fatty acid chains held together by

a glycerol• Store energy in the body

– Phospholipids: composed of 2 fatty acid chains held together by a glycerol

• Compose the cell membrane– Wax: composed of 1 fatty acid chain joined to an alcohol chain

• Waterproof and act as a protective coat– Steroids: does not have any fatty acid chains

• Many animal hormones are steroids

Nucleic Acids – TURN TO PAGE 60

• Very complex molecule with the following parts– Sugar backbone (deoxyribose)– Phosphate group– Nitrogenous base (used to link nucleic acid

strands together)

• Nucleotide: the monomer that makes up a nucleic acid strand

Nucleic Acids

• 2 main types of nucleic acids:– Deoxyribonucleic acid (DNA) – contains a

template that possesses all the information needed to produce and sustain a cell

– Ribonucleic acid (RNA) – transfers information from the DNA to ribosomes to produce protein

A View of the Cell

Plant cell

The History of the Cell

• The Cell–The basic unit of an organism–Discovery made possible by the invention of the microscope

Microscopes and Cells

• 1600’s.–Anton van Leeuwenhoek first described living cells as seen through a simple microscope.

Microscopes and Cells

–Robert Hooke used the first compound microscope to view thinly sliced cork cells.

•Compound scopes use a series of lenses to magnify in steps.•Hooke was the first to use the term “cell”.

Microscopes and Cells• 1830’s.

–Mathias Schleiden identified the first plant cells and concluded that all plants

made of cells.

- Thomas Schwann made the same conclusion about animal cells.

Cell Theory:

• All organisms are made up of one or more cells.

• The cell is the basic unit of organization of all organisms.

• All cells come from other cells all ready in existence.

Two Basic Cell Types

1) Prokaryote– Lacks internal

compartments.– No true nucleus.– Most are single-celled

(unicellular) organisms.– May or may not have a cell

wall– Examples: bacteria

Two Basic Cell Types2) Eukaryote

–Has several internal structures (organelles).

–True nucleus.–Either unicellular or multicellular.

unicellular example: yeast multicellular examples: plants and animals

6 Kingdoms of Life• Kingdom: the highest category for describing

similarities between organisms

• Prokaryotic– Eubacteria: traditional bacteria– Archaebacteria: “extreme” bacteria

• Eukaryotic– Protists– Fungi– Plant– Animal

Organization – from broadest to most specific• Kingdom

• Phylum

• Class

• Order

• Family

• Genus

• Species

The Parts of The Eukaryotic Cell1) Boundaries

A) Plasma Membrane - Serves as a boundary between the cell and its external environment.

- Allows materials to pass in and out of the cell. - “Fluid mosaic” model

1) Boundaries

B) Cell’s surface area vs. it’s volume

-- Because the ratio between volume and surface area do not increase at a constant rate, the size of the cell is limited

-- There is not enough surface area to import nutrients and export wastes

1) Boundaries

C) Cell Wall- Surrounds the plasma membrane of the cells of plants, bacteria, and fungi.- Plant cell walls contain cellulose while fungi cell walls contain chitin.

The Parts of The Eukaryotic Cell:2) Controls

A) Nucleus•Regulates cell function.•Surrounded by a double-layered membrane (nuclear enveloped) with large pores that allow materials to pass in and out of the nucleus.

•Contains chromatin – long tangles of DNA.

2) Controls

B) Nucleolus•Found in the nucleus and responsible for ribosome production. Ribosomes are the sites of protein production.

The Parts of The Eukaryotic Cell:3) Assembly

– Cytoplasm•The jelly-like material that surrounds the organelles.

– Cytosol•Part of the cytoplasm that contains small particles, but not membrane bound organelles

The Parts of The Eukaryotic Cell:4) Transport

A) Endoplasmic reticulum•Folded membrane that acts as the cell’s delivery system.

•Smooth E.R. contains enzymes for lipid synthesis.

•Rough E.R. is studded with ribosomes for protein synthesis.

4) Transport

B) Golgi apparatus (or Golgi body)•A series of flattened sacs where newly made lipids and proteins from the E.R. are repackaged and shipped to the plasma membrane.

The Parts of The Eukaryotic Cell: 5) Storage

A) Vacuoles•A sac of fluid surrounded by a membrane used to store food, fluid, or waste products.

5) StorageB) Lysosomes

•Contain a digestive enzyme.

•Can fuse with vacuoles to digest food, or can digest worn cell parts.

•Also known as “suicide sacs” because they can also destroy the whole cell.

The Parts of The Eukaryotic Cell: 6) Energy Transformers

Mitochondria•Produce the energy for the cell.

•Also known as the “powerhouse of the cell”.

•Has a highly folded inner membrane (cristae).

•Has its own DNA

6) Energy TransformersB) Chloroplasts

- Found in plant cells and some protists.-Transforms light energy into chemical energy which is stored in food molecules.-Contain chlorophyll – a green pigment that traps light energy and gives plants their green color.

The Parts of The Eukaryotic Cell: 7) Support

–Cytoskeleton•A network of thin, fibrous materials that act as a scaffold and support the organelles.

•Microtubules – hollow filaments of protein (structural support).

•Microfilaments – solid filaments of protein (aids movement).

The Parts of The Eukaryotic Cell: 8) Locomotion

1) Cilia•Short, numerous, hair-like projections from the plasma membrane.

•Move with a coordinated beating action.

8) Locomotion

B) Flagella•Longer, less numerous projections from the plasma membrane.

•Move with a whiplike action.

The Parts of The Eukaryotic Cell: 9) Cell Division

Centrioles– made of protein.– play a role in the splitting of

the cell into two cells.– found in animal and fungi cells.

Comparison between plants and animals

• Plants have every organelle that animals do, in addition to the following:– Cell wall: made from the carbohydrate,

cellulose, this gives the plant cell a much more rigid structure than animal cells

– Central vacuole: store water for the cell– Plastids (chloroplasts): usually involved in

photosynthesis or the storage of starches and other carbohydrates

Composite Animal Cell