Human biology Chapter 2, Human Biology Chapter 3

Cells

the basic building blocks of life

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Cytoplasm

A jellylike fluid inside the cell in which the organelles are suspended

Cell membrane

thin, flexible barrier around a cell; regulates what enters and leaves the cell

Cytosol

Liquid portion of cytoplasm

Cytoskelton

Internal scaffolding of protein fibres within the cytoplasm.

Organelles

structures suspended in the cytoplasm that carry out particular functions

Inclusions

chemical substances inside a cell, in the form of granules or droplets.

Nucleus

An organelle in a cell that contains DNA

nuclear membrane

a membrane that separates the nucleus of a cell from the cytoplasm.

Nuclear pores

small holes in the nuclear membrane, allowing material to enter and leave the nucleus

Ribosomes

is a small organelle involved in the process of making protein

Endoplasmic Reticulum

a network of membranes forming channels through the cytoplasm of a cell; it is used for storage, support, synthesis and transport within the cell.

Golgi Body (Apparatus)

packaging, processing, and secreting of proteins

Lysosomes

An organelle containing digestive enzymes

Mitochondria

Powerhouse of the cell, an organelle that is the site of ATP (energy) production

Cillia

Tiny hairlike extensions that move together in a sweeping motion

Flagella

A long, whip-like filament that helps in cell motility. Many bacteria are flagellated, and sperm are flagellated.

What does the cytoplasm consist of?

Microtubules: fine tubes that help maintain the shape of the cell and hold the organelles in place.

Microfilaments: protein fibres that move materials around the cytoplasm or move the whole cell.

The structure of the cell membrane

lipid bilayer of phospholipids and proteins

Functions of the cell membrane

Physical barrier: the membrane separates the cytoplasm from the extracellular fluid around the cell.

Regulates passage of materials: controls the movement of materials into and out of the cell.

Sensitive to changes: Is the first part of the cell affected by any changes in the extracellular fluid.

Supports the cell: the internal part of the membrane is attached to the microfilaments of the cell's cytoskeleton, giving support to the whole. cell and adjacent cells.

Transport across the cell membrane

Cell membranes are described as differentially permeable, semipermeable and selectively permeable. This means that they allow certain molecules to pass through, but restrict the movement of others. Materials pass through a cell membrane in different ways.

passive process: do not use energy

active process: use the cells energy

simple diffusion

The process of substances moving along the concentration gradient in a solution or across a semipermeable membrane, without the use of membrane proteins.

Diffusion

Movement of molecules from an area of higher concentration to an area of lower concentration.

Concentration

A measurement of the number of particles in a given volume

Concentration Gradient

difference in the concentration of a substance, often between the inside and outside of the cell.

Osmosis

Diffusion of water through a selectively permeable membrane from an area of high concentration to an area of low concentration.

facilitated transport

Proteins in the cell membrane that allow molecules to be transported across the cell membrane.

channel proteins

a protein that allows the small molecules to pass through the cell membrane

protein channel

A pathway through a protein in the cell membrane that allows the passage of substances across the membrane

carrier proteins

a protein that carries substances from one side of the membrane to the other

Carrier mediated transport

Transport of ions or molecules across a cell membrane by special carrier proteins

vescicular transport

The transport of materials into or out of a cell membrane

Endocytosis

process by which a cell takes material into the cell by the infolding of the cell membrane

Exocytosis

The process by which the content of the vesicles of the cells is pushed out through the cell membrane

What types of transport require energy and those that do not

Active: Active transport, Vesicular transport (endocytosis and exocytosis)

Passive: Simple diffusion, Osmosis, and Facilitated transport

Hypertonic

This solution has a higher solute concentration than the cell. Water moves out of the cell by osmosis, causing the cell to shrink.

Hypotonic

This solution has a lower solute concentration than the cell. Water moves into the cell causing it to swell

Cell Size

Small cells have a higher surface-area-to-volume ratio

metabolism

all the chemical reactions occurring in a living organism

catabolic metabolism

Processes by which larger molecules are broken down into smaller ones

anabolic metabolism

The process in which larger molecules are built from smaller ones; it requires enery.

Nutrients

a substance that provides nourishment essential for growth and the maintenance of life.

organic compounds

Compounds that contain carbon eg. carbohydrates, amino acids, protiens and lipids.

Carbohydrates

organic molecules that are the main source of enery for cells

Monosaccharides

1 sugar molecue: eg. glucose, fructose, galactose

Disaccharides

2 sugar molecules: eg. sucrose, lactose, maltose

Polysaccharides

many sugar molecules: eg. glycogen or cellulose

Lipids

large organic molecules made up of fatty acids and glycerol.

Triglycerides

the most common form of lipid, made up of glycerol and 3 fatty acids

Proteins

very large organic molecues made up of amino acids

Amino Acids

building blocks of proteins

peptide bond

a covalent bond that links amino acids together to form a protein.

Dipeptide

Two amino acids linked by a peptide bond.

Polypeptide

10 or more amino acids bonded together

Nucleic Acids

molecules containing many nucleotides forming a chain; including DNA and RNA

inorganic compound

A compound that does not contain carbon eg. water, oxygen. or having small molecules eg. carbon dioxide

aviation energy

energy needed to start a reaction

catalyst

substance that speeds up the rate of a chemical reaction

Enzyme

an organic substance that increases the speed of a chemical change without being changed

Substrate

Molecule upon which an enzyme acts.

active site

the part of a molecule that combines with the substrate

What is the effect of enzyme concentration on reaction speed?

When there are more enzymes, reactions happen faster because more enzyme molecules can react with substrates.

What happens to reaction speed when substrate concentration increases?

Increasing substrate concentration makes the reaction faster at first, but eventually stops increasing due to saturation of enzyme activity sites.

What is the effect of product buildup on enzyme reactions?

If products build up, the reaction slows down because substrates cannot easily reach the enzymes.

How does temperature affect enzyme activity?

Higher temperatures increase reaction speed up to an optimum of about 30-40 degrees Celsius in humans; above 40-50 degrees, enzymes denature and stop working.

What is the effect of pH on enzyme activity?

Enzymes work best at a specific optimum pH; if the pH is too high or too low, enzyme activity decreases.

Cofactor

the ions or inorganic molecules required by enzymes to catalyse a reaction

Coenzyme

non - potien organic molecules that are essential for the functioning of an enzyme

enzyme inhabitor

a substance that slows or stops an enzyme's activity

cellular respiration

The chemical reactions that make energy available for the cell

ADP (adenosine diphosphate)

The substance formed when the end phosphate group is removed from a molecule of ATP

ATP (adenosine triphosphate)

a molecule that stores energy in cells; the energy is stored in the bond between the end phosphate group and the rest of the molecule.

Glycolysis

The breakdown of glucose by enzymes, releasing energy and pyruvic acid.

Anaerobic Respiration

Respiration that does not require oxygen

aerobic respiration

Respiration that requires oxygen

1st step in cellular respiration

pyruvate -> Acetyl CoA - pyruvate is converted into acetyl CoA. To do this, carbon dioxide must be removed before entering the next stage. No ATP is produced in this step.

2nd step in cellular resperation

Krebs cycle—Acetyl CoA enters the cycle, carbon atoms are released as carbon dioxide, and 1 ATP is produced per acetyl CoA (2 per glucose)

3rd step in cellular resperation

electron transport system—electrons move through a chain using oxygen, forming water and producing most of the energy (about 26-34 ATP); total aerobic respiration can produce up to 38 ATP per glucose.