Unit 3: Molecules and Cells

Biochemistry

Molecules involved with cells; essentials to life from a chemical perspective

Organic Compounds

Contain carbon, mostly covalently bonded(ex. Glucose)

Inorganic Compounds

Lack carbon, simpler compounds

Important Inorganic Compounds

Water: Vital Properties, High heat capacity, solvent, chemical reactivity, cushioning

Salts

Easily disassociate into ions in the presence of water, vital to many body functions (sending messages, maintaining cell pressure, etc. Includes electrolytes; most plentiful are calcium and phosphorus

Acids

Can release detectable hydrogen ions(protein donor)

Base

Can release hydroxide ion (proton acceptor)

Important Organic Compunds

Carbohydrates, lipids, protein, nucleic acids, ATP

Carbohydrates

CHO(Carbon, Hydrogen, Oxygen) Includes sugar and starches Classified by size

monosaccharide

Simple sugar

Disaccarides

two single sugar joined by dehydration synthesis

polysaccharides

Long branching chains of linked simple sugars

Lipids

CHO(Carbon, Hydrogen, Oxygen) Carbon and Hydrogen outnumber oxygen Insoluble in water

Triglycerides(neutral fats),

Type of Lipid Found in fat deposits Composed of fatty acids and glycerol Source of Stored energy

Phospholipids

Form cell membranes

Steroids

Includes cholesterol, bile salts, vitamin D, and some hormones

Cholesterol

Basis for all steroids

Protein

CHON(Carbon, Hydrogen, Oxygen, Nitrogen), and sometimes sulfur Made of Amino Acids Accounts for over 1/2 of the body's organic matter Provides for construction materials for body tissues (fibrous & structural) Vital in cell function(Act as enzymes, hormones, and antibodies)

Nucleic Acids

CHONP(Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorus) Provides a blueprint for life Nucleotide bases- Adenine, Guanine, Cytosine, Thymine, Uracil(RNA) Makes DNA and RNA

Adenosine Triphosphate(ATP)

Derivative of nucleotide Chemical energy used by all cells Energy is released by breaking high-energy phosphate bonds Energy is replenished by the oxidation of food fuels

Anatomy of the cell

-Cells are organized into their main regions: Nucleus, cytoplasm, and Plasma membrane

Functions

Nucleus: Controls cell Cytoplasm: determines the transport Plasma Membrane: restricts/allows movement

Plasma Membrane

A barrier for all contents Double phospholipid layer: Hydrophilic head, hydrophobic tail Contains Protein, cholesterol, and glycoprotein

Cytoplasm

Material outside the nucleus and inside the plasma membrane Cytosol: Fluid that suspends other elements Organelles: Metabolic machinery of the cell Inclusions: Non-functioning units

Solutions

A homogeneous mixture of two or more components Solvent: dissolving medium (usually water) Solutes: Components within a solution (ex. ions, Na+, Cl-)

Intracellular fluid

fluid inside of the cell such as nucleoplasm and cytosol (Intra=within)

extracellular fluid(interstitial)

Fluid on the exterior of the cell (extra=beyond), (inter-between)

Membrane transport

Movement of a substance into and out of the cell

Selectively Permeable

Allows some substances to pass through while excluding others

Entrance factors

1. Size-huge molecules can't go through 2. Polarity: Extremely polar molecules can't pass through the nonpolar lipid tails of the cell membrane

Passive Transport

Relies on a concentration gradient -the movement of molecules from an area of high concentration to a region of low concentration -No energy is required

Types of passive transport

Diffusion(simple) Osmosis Facilitated diffusion Filtration-pressure gradient

Diffusion

Movement of molecules from areas of high concentration to areas of low concentration -Requires no energy expended by the cell -Molecules will reach a state of equilibrium

Osmosis

Diffusion of water molecules through a cell membrane

Facilitated Diffusion

Still passive diffusion; no energy expended by the cell Uses the concentration gradient (high to low concentration) to move large particles, polar molecules and ions

Active Transport

Low to High Requires the use of energy (ATP)

Types of Active Transport

Solute pumps (ex. Na+/K+ pump) Bulk Transport: -Exocytosis(exo=out) -Endocytosis(endo=in) Phagocytosis

Exocytosis

(exo=out of the cell) Used for big particles 1. Wraps around particle in a vesicle 2. Merge it with a cell membrane 3. Spit it outside the cell

Endocytosis

(endo=into the cell) 2 types 1st Phagocytosis: Solid particles Pinocytosis: For fluids 1. Cell comes and engulfs the particle 2. Wraps its membrane around the particle 2nd Receptor-Mediated Endocytosis