Biology AoS #1 Preparation Flashcards
What are integral proteins?
Proteins that are a permanent part of the membrane
What are transmembrane proteins?
Integral proteins that span the entire bilayer
What are peripheral proteins?
Proteins that a temporarily attached to the plasma membrane
What are the four functions of proteins?
- Transport
- Catalysis
- Communication
- Adhesion
What is the transport role for proteins?
Channels or pumps that control what enters and exits the cell, making the plasma membrane selectively permeable
What is the proteins role of catalysis?
Speeding up chemical reactions with the help of a protein group called enzymes
What is the proteins role for communication?
Receive or recognize cells and molecules. Often attached to the cytoskeleton to transmit signals into the cell.
What is the proteins role for adhesion?
Stick to other cells, the extracellular matrix, or the cytoskeleton
Describe the structure of carbohydrates.
Usually in chains that extend outside of the cell, rooted in the membrane to lipids or protein
Describe the function of carbohydrates.
Aid with cell-cell communication, signaling, recognition, of self or non self (foreign), molecules, and adhesion
Describe the structure of cholesterol.
Embeds itself between the fatty acid tails of the phospholipid bilayer in animal cell
What are the functions of cholesterol.
- Regulates the fluidity of the membrane
- At higher temperature, keeps membrane bound together
- At lower temperatures, it disrupts the fatty acid tails, stopping the phospholipids from becoming a solid boundary
What are the two main factors of the fluid mosaic model?
1) Molecules that make up the membrane aren’t held static in one place
2) Many different types of molecules are embedded in the plasma membrane
Define active transport
Movement of molecules across a semi-permeable membrane that requires energy
What are the two types of active transport?
- Protein mediated
- Bulk transport
What does protein mediated transport require?
Energy; usually in the form of ATP
Membrane proteins; protein carriers, protein channels
Brief version of steps for protein mediated transport?
1) Binding
2) Conformational change
3) Release
Describe the first step for protein mediated transport.
The target molecule for transport binds to a specific protein pump
Describe the second step for protein mediated transport.
Energy released from the reaction ATP = ADP + P which causes a conformational change within the protein pump.
Describe the third step for protein mediated transport.
The target molecule is pushed through the protein and released to the other side of the membrane
How many steps are there for protein mediated transport?
3
Where does the energy come from in step 2 of conformational change for protein mediated transport?
Energy comes from breaking the bond between the second and third phosphate ions in the ATP molecule
Is bulk transport passive or active transport?
Active
Define bulk transport
The movement of groups of molecules across the plasma membrane
What does bulk transport use?
Vesicles
What are the two forms of bulk transport?
Exocytosis and Endocytosis
Define exocytosis.
A type of active transport; bulk transport; involves molecules exiting the cell
Define endocytosis
A type of active transport; bulk transport; involves molecules entering the cell
How many steps are there in exocytosis?
3
What are the brief names for each three steps of exocytosis?
- Vesicle transport
- Fusion
- Release
Describe step one of exocytosis.
A vesicle containing secretory products is transported to the plasma membrane
Describe step two of exocytosis.
The membranes of the vesicles and cell fuse
Describe step three of exocytosis
Secretory products are released from the vesicle and out of the cell
What are secretory products?
Substances inside a vesicle that are being transported out of the cell.
What happens when the membranes of the vesicles and cells’ fuse?
When a vesicle fuses with the plasma membrane it adds phospholipids to the bilayer and makes the plasma membrane surface area slightly bigger
Why is endocytosis important?
It is important as many molecules the cell needs to survive are too large to take in through protein channels
It can also be an effective defense mechanism for the cell
One worded steps of endocytosis.
1) Fold
2) Trap
3) Bud
Describe the fold stage of endocytosis.
The plasma membrane folds inwards to form a cavity that fills with extracellular fluid and the target molecules.
Describe the trap stage of endocytosis.
The plasma membrane continues folding back on itself until two ends of the membrane meets and fuse. This traps the molecules inside the vesicle
Describe the bud stage of endocytosis
The vesicle pinches off from the membrane. It can then be transported to the appropriate cellular location
What are two types of endocytosis.
- phagocytosis
- pinocytosis
Define phagocytosis
Endocytosis for food particles and other solid materials
Define pinocytosis
Endocytosis of liquid or dissolved substances
Define passive transport.
The movement of molecules through a semi-permeable membrane and down the concentration gradient without an input of energy
What are the three types of passive transport?
- Diffusion
- Facilitated diffusion
- Osmosis
Define diffusion
The movement of particles down their concentration gradients
Occurs when molecules move from an area of high concentration to an area of lower concentration
Two features allowing molecules to diffuse freely
- Polarity
- Size
How does polarity affect a molecules ability to diffuse freely?
Nonpolar, uncharged, or hydrophobic molecules can cross the membrane as most of the plasma membrane is nonpolar
How does size affect a molecules ability to diffuse freely?
Small molecules like water are able to slip through the lipids in the phospholipid bilayer. However, if the molecule is highly charged, than it can not pass.
What affects the speed of diffusion?
Diffusion is faster when the concentration gradient is steeper - that is when there is a greater difference in concentration between intracellular and extracellular environments. It will also speed up at higher temperatures.
Define facilitated diffusion
Molecules that are too large or too charged to freely cross the plasma membrane can use a membrane protein, such as a protein channel, to move down their concentration gradient into or out of the cell
What are protein channels?
Pores or holes in the membrane that let specific substances through
What are carrier proteins?
Proteins that bind to the substance that is being transported and undergo a conformational change to push the substance down its concentration through to the other side of the membrane. They return to their original shape once the molecule has been transported
What is conformational change?
A change in three dimensional shape of macromolecules such as proteins
Does diffusion (simple) require a protein?
No.
Define osmosis
The diffusion of water from an area of low solute to an area of high solute concentration
What property of cells does tonicity effect?
Size
Do all cells have a plasma membrane?
Yes
What does the plasma membrane separate?
The intracellular from the extracellular environments
What is the name of the bilayer that makes up the plasma membrane
The phospholipid bilayer
What is another name for the plasma membrane?
The cell membrane
What is the main component of the plasma membrane?
Phospholipids
What two main components make up a phospholipid
Phosphate head, two fatty acid tails
What is the phosphate head in the plasma membrane made up of?
Made of glycerol and phosphate group
What charge do the phosphate heads have?
Negative
Is the phosphate head hydrophilic or hydrophobic?
Hydrophilic
Hydrophilic means in two words
Water loving
Is the phosphate head polar or nonpolar?
Polar
What are the two fatty acid tails made up of?
Long chains of carbon and hydrogen
What charge do the two fatty acid tails have?
No charge
Are the fatty acid tails hydrophilic or hydrophobic?
Hydrophobic
Are the fatty acid tails polar or nonpolar?
Nonpolar
Hydrophobic in two words
Water fearing
The fatty acid tails form what portion of the bilayer?
Middle
What are amphipathic molecules?
Molecules that have both hydrophobic and hydrophilic parts
Is the plasma membrane amphipathic?
Yes
What is another name for amphipathic?
Amphiphilic
Animal cell reaction in a hypotonic solution.
Lysed
Plant cell reaction in a hypotonic solution
Turgid
Animal cell in an isotonic solution.
Normal
Plant cell in an isotonic solution.
Flaccid
Animal cell in a hypertonic solution
Shrivelled
Plant cell in a hypertonic solution
Plasmolysed
What are eight qualities that all living things possess
- Movement
- Respiration
- Sensitivity
- Growth
- Reproduction
- Equilibrium
- Excretion
- Nutrition
3 things that the cell theory states
- All living things are made up of cells
- Cells are the smallest and most basic units of life
- All cells come from pre-existing cells
What two categories can ALL organisms be classified as
Eukaryotic and Prokaryotic
The six kingdoms of life
- Animalia
- Archaea
- Bacteria
- Fungi
- Plantae
- Protista
What 4 things do both eukaryotic and prokaryotic cells have in common?
- Plasma membrane
- Cytosol
- Ribosomes
- DNA
Do eukaryotes have membrane bound organelles?
Yes
Do prokaryotes have membrane bound organelles?
No
Explain the DNA organization in eukaryotes
More than one linear strand of DNA packaged in a chromosome in a nucleus
Explain the DNA organization in prokaryotes
One circular chromosome and additional plasmids
Eukaryotic organism nature
Can be unicellular or multicelluar
Prokaryotic organism nature
Unicellular
Which is larger in size
Eukaryotes or prokaryotes?
Eukaryotes are larger in size than prokaryotes
Eukaryotic methods of cell replication
Mitosis and Meiosis
Prokaryotic method of cell replication
Binary fission
Three domains of living things
- Archaea
- Bacteria
- Eukarya
Which of the three living domains are prokaryotic domains?
Archaea and Bacteria
Which of the three living domains are eukaryotic domains?
Eukarya
What are the four kingdoms of Eukarya?
- Animalia
- Fungi
- Plantae
- Protista
How many kingdoms are there of life?
6
Animalia - type of organism
Eukaryotic
Archaea - type of organism
Prokaryotic
Bacteria - type of organism
Prokaryotic
Fungi - type of organism
Eukaryotic
Plantae - type of organism
Eukaryotic
Protista - type of organism
Eukaryotic
Animalia - organism nature
Multicellular
Archaea - organism nature
Unicellular
Bacteria - organism nature
Unicellular
Fungi - organism nature
Unicellular or multicellular
Plantae - organism nature
Multicellular
Protista - organism nature
Unicellular or multicellular
Are archaea living things?
Yes
Does cell theory apply to all living things?
Yes
What is the nucleus’ role?
To protect and confine genetic information (DNA) of the cell
What smaller structure is inside the nucleus?
Nucleolus
What does the nucleolus produce?
Ribosomes
Where can ribosomes be found in the cell?
They can float freely in the cytoplasm or be attached to the rough endoplasmic reticulum
What do ribosomes help make?
Proteins
What is the rough endoplasmic reticulum’s job?
To synthesize and modify proteins