Cells Biology Year 11 T2

Prokaryotes

Primitive cells with a simple structure that lack membrane-bound organelles; e.g. bacteria.

Eukaryotes

More complex cells that contain membrane-bound organelles; e.g. cells that make up animals and plants.

Mitochondria

Organelles that produce energy in the form of ATP through respiration.

Chloroplast

Organelle found in plants where photosynthesis takes place.

Cell Membrane

The outer boundary of the cell that controls the passage of substances in and out.

Isotonic solution

A solution with the same solute concentration as the inside of the cell.

Hypotonic solution

A solution with a lower solute concentration than that inside the cell.

Hypertonic solution

A solution with a higher solute concentration than that inside the cell.

Diffusion

The movement of molecules from an area of high concentration to an area of low concentration.

Osmosis

The diffusion of water across a selectively permeable membrane.

Facilitated Diffusion

The process by which molecules move through channel proteins in the cell membrane.

Concentration Gradient

The difference in concentration of a substance across a membrane.

Surface Area to Volume Ratio

A measure used to compare the surface area of a cell to its volume, affecting material exchange.

Rough ER

Endoplasmic reticulum with ribosomes that makes and modifies proteins.

Smooth ER

Endoplasmic reticulum that synthesizes lipids and detoxifies certain chemicals.

Ribosomes

Cell organelles made of RNA and protein that synthesize proteins.

Lysosomes

Membrane-bound vesicles containing digestive enzymes that break down waste.

Golgi Body

An organelle that processes and packages substances made in the cell.

Prokaryotes

Primitive cells with a simple structure and no membrane-bound organelles.

Eukaryotes

Complex cells with membrane-bound internal structures.

Mitochondria

The process of energy production in the form of ATP; glucose + oxygen → CO2 + Water + energy.

Chloroplast

Organelle in plants where photosynthesis takes place.

Cell Membranes

Controls the passage of water and other molecules into or out of the cell.

Lipid Component

Fluid component of the cell membrane made of two layers of phospholipids.

Protein Component

Molecules scattered throughout the lipid bilayer forming channels.

Carbohydrates

Attached to the cell membrane and play a role in recognition.

Hydrophilic Head

The 'head' of the phospholipid.

Hydrophobic Tail

The tail of the phospholipid.

Cell membrane

The sack/border of the cell

Cytoplasm

Fluid within the cell

Organelles

The floating things each serving a different purpose

Nucleus

Contains the cells genetic information needed for growth, repair, and responsible for telling the cell what to do.

Nucleolus

Makes Ribosomes

Ribosomes

Made of ribosomal RNA and protein, make proteins, found attached to the endoplasmic reticulum

Endoplasmic Reticulum (ER)

Network of flattened, interconnected membranes connected to nucleus

Rough ER

Has ribosomes; Makes and modifies protein

Smooth ER

No ribosomes; Make lipids (Fat)

Golgi Body

Made of flat membrane sacs stacked on top of each other. Job is to process and package substances the cell has made

Lysosomes

Digest cell waste. Membrane bound sacs that contain digestive enzymes. Needed to break down other substances

Simple Diffusion

Molecules move from area of HIGH to LOW concentration

Diffusion

PASSIVE process which means no energy is used to make the molecules to move

Diffusion through a membrane

Solute moves DOWN the concentration gradient (HIGH to LOW)

Facilitated Diffusion

Molecules move through a cell membrane through a channel protein

Channel proteins

embedded in the cell membrane and have a pore for materials to cross

Carrier proteins

can change shape to move material from one side o f the membrane to the other

Osmosis

Diffusion of water across a membrane

Isotonic

A solution whose solute concentration is the same as the solute concentration inside the cell

Hypotonic (LOW)

A solution whose solute concentration is LOWER than the solute concentration inside a cell

Hypertonic (HIGH)

A solution whose solute concentration is HIGHER than the solute concentration inside a cell

Concentration Gradient

The concentration gradient is the difference in concentration of a substance across a membrane

Surface Area

Surface Area will determine the exchange of materials between the cell and its environment

Active Transport

Active transport is the movement of molecules form a region of LOW concentration to a region of HIGH concentration

Phagocytosis

Solid particle

Pinocytosis

Fluid

Endocytosis

WHEN A SOLID/FLUID IS GOING INTO THE CELL

Exocytosis

WHEN A SOLID/FLUID IS GOING OUT OF THE CELL

Magnification

The degree to which an image is enlarged compared to the original object.

Resolution

The ability to distinguish between two points that are close together; clarity of an image.

Condenser Lens

Concentrates light onto the specimen in a microscope.

Objective Lens

The primary lens that magnifies the specimen in a microscope.

Ocular Lens

The eyepiece lens that further magnifies the image from the objective lens.

Artefacts in Microscopy

False structures or features introduced during sample preparation that are not present in the original specimen.

Compound Light Microscope

200 nm,

15,000x resolution

Fluorescence Microscope

Modified light microscope that highlights specific parts of a cell. High-intensity light source causes fluorescent parts of cell to light up. Useful for seeing structures beyond the resolution limit of standard light microscopes.

Electron Microscopes

Use electron beams.

much higher magnification

greater resolution

Can view subcellular

Scanning Electron Microscope (SEM)

Electrons bounce off the surface of a specimen.

Produces 3D images of surfaces.

Resolution: 10 nm

Confocal Laser Scanning Microscope

Uses a laser to scan the specimen point by point at different depths. Creates detailed 3D images of intact cells. Useful for studying the structure of cells without damaging them.

Limitations of Electron Microscopes

Cannot view living specimen

Expensive and large; require high maintenance.

Light microscope resolution range

Can’t see below 200 nm. Can’t show organelles in depth.

Chemicals In Cells

Chemicals and ions required for cells to function, split into organic and inorganic groups.

Organic Chemicals

Contain Hydrogen, Oxygen, Carbon; derived from living organisms. Includes carbohydrates, lipids, proteins, and nucleic acids.

Monosaccharides

Basic subunit of carbohydrates.

Disaccharides

Two monosaccharides joined together.

Polysaccharides

More than two monosaccharides joined together.

Lipids

Energy storage molecules, including fats and oils.

Proteins

Contain nitrogen, carbon, oxygen, and hydrogen; more complex than lipids and carbohydrates. Subunits are amino acids joined by polypeptide bonds.

Nucleic Acids

Genetic material of all organisms; includes DNA and RNA. Subunits are nucleotides.

Inorganic Chemicals

Includes water, oxygen, carbon dioxide, and nitrogen.

DNA

Genetic material of all organisms

RNA

Genetic material of all organisms

Hetertrophs

‘consumers’, eat organic matter

Autotrophs

Make their own food, plants

what are Enzymes

Catalysts of chemical reactions,

Protein

Each enzyme works on SPECIFIC substrate

What is the active site

Region where reaction occurs, substrate binds with enzymes

Induced fit model

Enzyme molds shape to fit the substrate

Lock and key model

Enzyme doesn’t change shape, substrate is tight

Enzyme vs temperature

Optimal = 37*C

Denatures at 40*C

Enzyme vs pH

optimal = 7

above 7, enzyme becomes less efficient

Enzyme vs substrate concentration

½ Vmax + Vmax

All substrates sites are active = plateu

Purpose of Xylem

Transport water from roots to rest of plant

Purpose of phloem

Transport sugars and nutrients around plant from sources to sinks

Sinks

Anywhere sucrose is used or removed

Sinks

Anywhere sucrose is produced (chloroplast)

what is the Cohesion tension model

model explaining how water can travel up plant

what is cohesion

tendency for water molecules to stick together

what is adhesion

tendency for water molecules to stick to other substsances

What is active transport

• Survival mechanism

• Low to high

• Protein channel

Passive transport

No energy required,

High to low

facilitated diffusion

passive but molecules are too big, must go through channel protein

Stomata

• underside of leaf

• Diffusion of gasses occurs

• surrounded by guard cells