Biology Unit 1- AOS 1

What are cells?

Cells are the building blocks of life

Unicellular

Organisms made of one cell

Multicellular

Organisms made of multiple cells

The Cell Theory

All Living things are made from cells

Cells are the basic structural and functional unit of life

Cells come from pre-exisitng cells through cell division

Types of cells

Prokaryotes

Eukaryotes

Characteristics of Prokaryotes

No membrane bound organelles

Have ribosomes

Free floating DNA

No defined nucleus

Small and simple cells

Characteristics of Eukaryotes

Large and Complex

Have Membrane bound organelles

defined nucleus

Example of Eukaryote

Plant and Animal cells

Example of Prokaryote

Bacteria

Plant Cell Characteristics

Large Permanent vacuole

Chloroplasts

rigid cell wall

Animal Cell

Small and Temporary vacuole

No chloroplasts

No cell wall

Organelles in Eukaryotes

Nucleus

Plasma Membrane

Cytoplasm

Cell wall

Vacuole

Chloroplast

Mitochondria

Ribosomes

Rough ER

Smooth ER

Golgi Body

Lysosomes

Nucleus function

stores and protects the DNA, which contains the instructions for cellular activity.

Cell wall function

Provides structure and creates shape to the cell

Vacuole function

Stores nutrients of the cell and waste products.

Chloroplast

Site of photosynthesis to convert light into energy for plants

Mitochondria

Produces ATP to fuel the cell’s activities through a process called cellular respiration.

Ribosomes

Site of protein synthesis.

Rough ER

Folds and sorts proteins

Smooth ER

lipid and steroid synthesis and hormone production

Golgi Body

Processes and packages lipids within the cell

Lysosomes

Breaks down and recycles cellular waste and debris

Average Cell size

Most cells are between 2 micrometers and 200 micrometers in size

What is Diffusion?

Simple diffusion is a passive process and occurs without energy

How does diffusion move the particles?

Diffusion moves the solutes down a concentration gradient from high to low concentration.

What are the molecules trying to achieve when diffusing?

The molecules are trying to reach equilibrium .

What is the volume of a cell?

The amount of cytoplasm (cytosol+ organelles)

What does the cytoplasm of a cell determine?

Determines how many resources a cell needs and how much waste it produces.

What is the surface area of a cell?

The surface of the plasma membrane surrounding the cell

What does the plasma determine?

Allows substances to move into and out of the cell

What happens when the size of a cell increases?

Its volume generally increases faster than its surface area.

Which SA:V ratio allows for efficient exchange of materials?

A greater surface area to smaller volume or higher SA:V ratio allows cells to exchange materials with the environment more efferently.

Examples of high SA:V ratio?

Villi and microvilli in the small intestine

Shape of RBC

Volume general definition

Volume is the amount of space within an object (cm³)

Surface Area general definition

Surface area is the sum of the area of all exposed sides of a 3D shape (cm²)

How to calculate Volume

Length x Width x Height

How to calculate Surface Area

(Length x Width) x 6 sides

Surface Area to Volume Ratio calculation

Surface area/ volume

Which size of cubes have a higher SA:V ratio?

Smaller sized cubes will have a higher SA:V ratio.

What happens if cells get too large?

They would die from lack of resources or be poisoned from the build-up of waste products due to the slow rate of diffusion.

Bigger vs Smaller cells

Bigger cells have a greater metabolism than smaller cells

They require more resources to function

Bigger cells have less surface area for the exchange of these resources.

Which cells have a higher SA:V ratio?

Long, thin or folded cells

Why are RBC cells so great at exchanging of materials?

The shape of RBC increases their SA:V ratio and increases efficiency of diffusion of oxygen and carbon dioxide into and out of the cell

Why are Villi and Microvilli so great at exchanging materials?

Villi and microvilli increase the surface area for nutrients to be absorbed in the small intestine.

Name 4 locations where membranes are found:

Any membrane bound organelles within eukaryotic cells.

What is a key characteristic of the plasma membrane?

The plasma membrane is flexible and able to break and repair easily.

Example of a cell that has a flexible plasma membrane

Certain WBC called phagocytes engulf pathogens such as bacteria

Why is the Plasma Membrane important?

Membranes separate internal cellular environment from the extracellular environment.

Other functions of the plasma membrane

Allows specific molecules to enter and exit the cell

Site for some biochemical reactions

Allows for cell to change shape

Cell communication

Self vs non-self recognition (immunity)

Plasma membrane main components

Phospholipids

Proteins

How are the phospholipids arranged to make the main structure of the plasma membrane?

They are arranged into a phospholipid bilayer

What are phospholipids made of?

Phospholipids have phosphate heads and a lipid tail

Phosphate head characteristics?

Hydrophilic

Polar body

How do polar bodies cross the plasma membrane?

They require a protein to cross the membrane.

Lipid Tail characteristics?

Hydrophobic

Non-polar

How do non-polar bodies cross the plasma membrane?

They diffuse directly across the membrane not requiring any protein to help.

Polar molecules charge

uneven distribution of change, creating a positive and negative end, creating a dipole

Non-polar molecules charge

even distribution of charge, lacking a dipole

Phospholipid arrangements

The phospholipid heads are attracted to water and the fatty acid tails are repelled by water

This causes the phospholipids to arrange themselves in specific ways in different environments.

Types of proteins in the plasma membrane

Integral

Transmembrane

Peripheral

What are Integral proteins?

They are permanently attached to the plasma membrane

What are Transmembrane proteins?

They are a type of integral protein that spans the phospholipid bilayer

What are Peripheral proteins?

They are temporary proteins that attach to the outside of the plasma membrane

Protein functions in the plasma membrane

Transport

Catalysis

Communication

Adhesion

Transport proteins

Channels or pumps that control what enters and exits the cell

Catalysis proteins

speeds up chemical reactions

Communication proteins

Receives signals and recognizes cells and molecules

Adhesion proteins

Sticks to other cells

What do carbohydrates do in terms of the plasma membrane?

Carbohydrates can form chains that are attaches to phospholipids forming glycolipids or proteins forming glycoproteins.

What are glycoproteins?

They are carbohydrate chains attached to a protein.

What are glycolipids?

They are carbohydrate chains attached to a phospholipid.

What does cholesterol do in the plasma membrane?

Cholesterol embeds in the membrane between fatty acid tails of the phospholipids to prevent them from freezing in cold temperatures.

What is The Fluid Mosaic model?

The fluid mosaic model describes the structure of the plasma membrane as a mosaic of components.

What does the fluid mosaic model contain?

Phospholipids

Cholesterol

Proteins

Carbohydrates

What component of the plasma membrane gives a fluid characteristic?

The phospholipids give the membrane a fluid characteristic because they continually move in the membrane.

How do the other components in the phospholipid bilayer move?

The proteins and other components can move freely within the phospholipid bilayer.

What does semi-permeability of the plasma membrane mean?

It means that the plasma membrane only allows certain materials to enter and exit the cell

How is crossing the plasma membrane described as?

As the cell membrane only allows some dissolved substances to cross it, it is described as being semi permeable or partially permeable.

What must all cells be able to do?

They must be able to take in and expel various substances to survive, grow and reproduce.

What are the two types of transport in a plasma membrane?

Passive Transport

Active Transport

Does Passive Transport require energy?

Passive transport doesn’t require energy (ATP)

Does Active Transport require energy?

Active transport requires energy (ATP)

What are the three types of passive transport?

Simple diffusion

Facilitated diffusion

Osmosis

What is simple diffusion?

Simple diffusion is the net movement of particles from a region of high concentration to a region of low concentration through a semi-permeable membrane without the input of energy (ATP)

What is movement from a high to low concentration known as?

Moving down their concentration gradient.

How do particles move through the plasma membrane in simple diffusion?

The particles move between the phospholipids.

How does diffusion move solutes?

Diffusion moves solutes down a concentration gradient until the molecule reaches equilibrium.

What are solutes?

Solutes are dissolved substances.

What are the factors that INCREASE diffusion?

Large concentration gradient

Higher temperatures

Small molecules

Movement through a gaseous membrane

What substances can move through the plasma membrane via simple diffusion?

Small unchanged molecules

Lipid soluble molecules

Small non-polar molecules

Hydrophobic molecules

Examples of substances that can move through the plasma membrane via simple diffusion.

Water

Carbon Dioxide

Oxygen

What is facilitated diffusion?

Facilitated diffusion is the net movement of molecules down their concentration gradient through protein channels or protein carriers without the input of energy (ATP).

Does facilitated diffusion move down its concentration gradient?

Yes it moves from a high to low concentration gradient.

What are Protein channels?

Protein channels are pores in the plasma membrane that let specific substances through.

What is a characteristic of a protein channels do?

They can be gated or non-gated meaning they can open or close

What are carrier proteins?

Carrier proteins bind to a molecule and undergo a change in shape to push the substance down its concentration gradient

They return to their original shape after

What is the specificity of Channels and Carrier proteins?

Channels and carrier proteins are specific to the molecule they transport, this contributes to the selective permeability of the plasma membrane

What substances can travel across the plasma membrane via facilitated diffusion?

Large or Charged molecules

Water soluble molecules

Polar molecules

Examples of substances that can travel across the plasma membrane via facilitated diffusion

Amino acids

Simple sugars

Ions

What is osmosis?

Osmosis is the net movement of water across a semi-permeable membrane from a region of high to low water concentration without the input of energy (ATP).