Chapter 2 and 3 - Cell Structure, Tissues, Enzymes and Metabolism

Materials that pass from the tissue fluid to the cell

• Oxygen

• glucose

• water

• iron

• sodium

List waste materials and useful products that pass from cytoplasm to the tissue fluid.

• Carbon dioxide

• Nitrogenous wastes (urea, uric acid, creatinine)

Describe the Fluid Mosaic Model

Fluid = The proteins in the membrane are constantly moving

Mosaic = The random arrangement of proteins

Phospholipid molecule

A lipid molecule that contains a phosphate head and a lipid tail.

Bilayer

Two layers of phospholipids that make up a single membrane.

Hydrophilic

Water-loving

• Phosphate heads are hydrophilic

Hydrophobic

Water-hating

• Lipid tails are hydrophobic

3 Components that make up cell theory

1. cells are the basic unit of life.

2. all living things are made up of cells

3. all cells come from other cells

5 structures that make up a human cell

1. cell membrane

2. cytosol

3. cytoskeleton

4. cytoplasm

5. organelles

Cell Membrane

• a double layer of phospolipids and cholesterol molecules

• separates cell contents from the environment outside the cell. controls what enters and leaves the cell.

Cytosol

• the liquid part of the cytoplasm

cytoskeleton

• consists of a network of micro tubules and microfilaments

• creates cell shape and allows movement in the cell

cytoplasm

• jelly-like material that fills the space between the nucleus and the cell membrane

• the material in which the cell’s contents are suspended in

Nucleus

• oval/spherical shaped and the largest organells

• stores and protects DNA and controls cell’s activities

Nucleolus

• spherical organelle inside nucleus

• produces ribosomes

nuclear membrane

• a double membrane containing holes called nuclear pores

• separates the nucleus from the cytoplasm

nuclear pores

• holes in the nuclear membrane

• regulates the transport of molecules between nucleus and cytoplasm

Ribosomes

• very small spherical organelles

• at ribosomes, amino acids are joined together to make proteins

Endoplasmic Reticulum

• pairs of parallel membranes connected to the nuclear membrane (granular ER has ribosomes)

• the membranes of the ER provide a surface for chemical reactions, while the channels are fore storing or transporting molecules.

Golgi Body

• series of flattened membranes stacked one upon the other

• modifies protein and packages them for secretion from the cell inside vesicles.

Lysosomes

• small spheres bound by a membrane, that are formed from the Golgi body

• contain digestive enzymes and break down excess or worn-out cell parts. also destroy invading viruses and bacteria.

Mitochondria

• oval shaped structures that contain folds on inner membrane

• chemical reactions on inner membrane make energy for cell from food molecules, oxygen, and water.

Centrioles

• barrel shaped organelle made up of micro tubules

• necessary for cell division

vacuole

• storage area for waste products

Functions of the cell membrane

• cell membrane provides a physical barrier for the different composition of chemicals on either side.

• regulates the entry of essential substances and the exit of wastes.

• receptors respond to changing external changes

• provides structure to the cell

4 types of protein found on the cell membrane

• channel proteins

• carrier proteins

• cell identity markers

• cholesterol

Why the cell membrane is described as “differentially permeable”

the membrane controls what substances can cross in or out of the cytoplasm

Another name for “differentially permeable”

• Semi permeable

• selectively

diffusion

• movement of particles randomly from areas of high concentration to low concentration.

• down a concentration gradient.

• gas and liquid molecules are constantly moving in random directions until they hit another molecule during diffusion.

diffusion gradient

• a difference in concentration between two areas.

• areas are usually cytoplasm and extracellular fluid.

Simple diffusion

• O2 and CO2 can diffuse through the phospholipid bilayer

• Alcohol, steroids, and fat-soluble substances can diffuse through the lipid portions of the membrane

Osmosis

• movement of water from areas of high concentration to low concentration

• protein channels speed up the process of osmosis

carrier-mediated transport

Transport of substances across the cell membrane using carrier proteins

Facilitated diffusion

• movement of large molecules (glucose) using carrier proteins

• passive movement from high conc to low conc

• diffusion speed limited by number of carrier proteins

Active transport

• movement of substances from areas of low conc to high conc using carrier proteins

• requires energy (ATP)

ATP

Adenosine Triphosphate

Substances transported through facilitated diffusion

• glucose

• amino acids

Substances transported through active transport

• certain ions

• glucose

• amino acids

Vesicular transport

• movement of substances in and out of cell enclosed in vesicles

• an active process that can move bulk quantities of solid or liquid particles

Endocytosis

• movement of substances into cell

• cell membrane folds around a droplet of liquid/solid particle until enclosed. vesicle formed then pinches off and is suspended in cell cytoplasm

• phagocytosis = taking in solid particles

• pinocytosis = taking in liquid particles

• E.g. cholesterol, iron ions

Exocytosis

• removing substances from the cell using vesicles

• when the contents of vesicle inside the cell are passed to the outside, the vesicle migrates and fuses to the membrane, releasing the contents into the extracellular fluid.

• E.g. digestive enzymes, milk from breast cells, saliva from salivary gland cells

Levels of organisation in body

1. Cells

2. Tissues

3. Organs

4. System

5. Organism

What is a tissue

• a group of cells that are similar in structure and work together to carry out a particular task

4 basic types of tissue

1. Epithelial

2. Connective

3. Muscular

4. Nervous

Matrix

the non-cellular material between the cells in tissues

Epithelial Tissue

• covers body surfaces and cavities

• the cells are very closely joined together

• the shape of the cells varies, they can be thin and flat, column-shaped, or cube-shaped

Places you will find epithelial tissue

• outside of heart, kidneys, intestines, liver and lungs

• inner layer of heart, stomach, intestines

Ciliated Epithelium

• epithelial cells with cilia on the outside surface of the cell

• in the respiratory system, CE lines the trachea, bronchial tubes, and the

Connective Tissue

• the tissue that provides support for the body and helps to hold all the body parts together.

• the cells are not close together and are instead separated by large amounts of matrix.

Places you’ll find connective tissue

• Bones

• cartilage

• tendons/ligaments

• adipose

• blood

why blood is unique

blood cells are suspended in liquid matrix - also known as plasma

Muscular tissue

• the cells of muscular tissue (often called muscle fibers) are long and thin and can contract to become shorter

the 3 types of muscular tissue

• skeletal

• smooth

• cardiac

Skeletal Muscle

• makes up the muscle attached to bones

• voluntary muscle - we can move the muscles when we want to

• striated - skeletal muscle has stripes or striations across them

Smooth muscle

• non-striated - does not have any striations

• involuntary - we cannot contract smooth muscle voluntarily

• found in the walls of stomach, intestines, blood vessels

Cardiac muscle

• aka heart muscle

• makes up most of the heart

• cardiac muscle is involuntary

• striated

homeostasis

maintenance of a stable internal environment

cilia

hairlike projections that extend from the cell membrane, helps move the cell or materials across the cell surface

flagella

long projection from a cell that helps them move.

found on sperm cells.

Nervous tissue

• made up of cells called neurons which have long projections from the body part of the cell.

• upon stimulation, messages can be carried along the projections throughout the body

• found in the brain, spinal chord, and the nerves

Enzyme

• a protein that speeds up a reaction, but is not changed by the reaction

• an organic catalyst

• decreases the amount of activation energy needed to make a reaction happen

• allows reactions to occur fast enough for body requirement, without them, body reactions would be too slow.

Substrate

molecules that enzymes react with

Active site

the part of the enzyme molecule that combines with the substrate

product

what is formed after the substrate has interacted with the enzyme

Enzyme-substrate complex

the structure that forms when an enzyme attaches to the substrate is it reacting with

Catabolic reaction (catabolism)

when a substrate is broken down into smaller products

Anabolic reaction (anabolism)

when substrates are combined to produce a larger product

factors that affect enzyme activity

• concentration - higher conc of substrates or enzymes leads to more reactions

• temperature - higher temp leads to faster reactions (30-40 degrees is optimal)

• pH - enzymes have an optimal pH where they are most effective

• cofactors - substances that can change the shape of the active site (vitamins are a coenzyme, which is a type of cofactor)

Denature

• enzymes have to be kept within certain limits or else they will denature

• denature = means to change shape, generally at the active site. when an enzyme denatures, substrates can’t bind to the active sites.

• usually irreversible

• caused by a change in condition - temp or pH

cellular respiration

• occurs in every cell to supply the cell with the energy it needs and to produce heat

• needs energy to make new molecules, build membranes and organelles, and moving substances in and out of cell

Where a cell gets energy from

• glucose, amino acids, fatty acid and glycerol can be broken down to a form the cell can use

• extra energy is stored in an ATP molecule

Cellular respiration equation

C₆H₁₂O₆ + 6O₂ > 6CO₂ + 6H₂O + ATP

ATP

• Adenosine Triphosphate

• a molecule made up of an adenine, ribose, and 3 phosphate groups

• mobile - can move around the cell

How ATP works

• energy is stored in the bonds between the second and third phosphate group

• when the bond is broken, energy is released and ADP is formed

Respiration

• the process of breaking down food molecules to release energy

• occurs in the mitochondria

2 types of respiration

• Aerobic - requires oxygen

• Anaerobic - requires an absence of oxygen

Glycolysis

the breakdown of a glucose molecule into pyruvic acid; it releases energy to form 2 ATP molecules

Citric Acid Cycle/Krebs Cycle

the series of reactions that occur in the mitochondria during aerobic respiration where Acetyl CoA enters and CO₂ is released

Electron transport system/Oxidative phosphorylation

a series of chemical reactions where oxygen is required. here, electrons are passed between molecules resulting in oxygen molecules forming water, along with up to 34 ATP molecules

Oxygen debt

extra oxygen required, in addition to the normal resting requirement to remove the lactic acid produced during exercise.

recovery oxygen

the extra oxygen needed to recover after exercise

adenosine diphosphate

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