Cells And Enzymes Flashcards
What is the three dimensional structure of a eukaryotic cell maintained by and what does it consist of
-cytoskeleton
-consists of interconnected protein filaments in the cytoplasm
What is the pH of the cytoplasm
7.2
What is the pH in extracellular fluid
7.4
What is the average diameter of a cell
10-20 microns
Why is it useful to use red blood cells to measure other cells
-have a diameter of 7 microns and are considered the smallest cells
Primary structure of a cell membrane is made up of ………….
Phospholipids
Phospholipids have a ……….. head and …………… tails
1.hydrophilic
2.hydrophobic
Why does health of the individual depend on the normal functioning of cells in the body
-Cells which don’t normally function can lead illnesses such as cancer or heart disease
-e.g. cancer is caused when cells divide uncontrollably and spread into surrounding tissues
What happens when you shake water and phospholipids together
Forms a micelle
what are the membrane components and how do they affect movement of substances across cell membranes
*PHOSPHOLIPID BILAYER
-Allows diffusion of non-polar small/lipid-soluble
molecules e.g. oxygen or water, down a concentration gradient
- Restricts the movement of larger/polar molecules
*CHANNEL PROTEIN
-allow diffusion of water soluble substances (facilitated diffusion)
*CARRIER PROTEINS
-allow diffusion of slightly larger substances (facilitated diffusion)
-allow active transport of substances against a concentration gradient
*CHOLESTEROL
-restricts movement of other molecules making up membrane -> decreases fluidity and permeability
Function of a nucleus
-Control centre of the cell
-responsible for transmitting genetic information and providing the instructions for protein synthesis
What is this organelle?
Nucleus
What is the function of ribosomes
-Protein synthesis- a place where mRNA is translated into protein.
-It contains rRNA and proteins
Which organelle is this ?
Ribosomes
What is the rough endoplasmic reticulum and its function
-Sugar groups are attached to proteins within the cisterns.
-Proteins are bound in vesicles for transport to the golgi apparatus and other sites.
Which organelle is this
Rough endoplasmic reticulum
What is the function of mitochondria
-Site of ATP synthesis; powerhouse of the cell.
-Energy production through aerobic metabolism and Ketogenesis
What is ketogenesis
A metabolic pathway that produces ketone bodies which provide an alternative form of energy for the body
Which organelle is this
Mitochondria
What is the Golgi apparatus and its function
-Group of fluid-filled membrane bound flattened sacs.
-Packages, modifies, and segregates proteins for secretion from the cell, makes lysosomes, and incorporation into the plasma membrane
Which organelle is this ?
Golgi apparatus
What are lysosomes and what are their functions
-Sites of intracellular digestion- contains enzymes called lysozymes.
-Can be used to digest invading cells or break down worn out components of the cell. pH= 4.8
Which organelle is this?
Lysosomes
What is the function of the smooth endoplasmic reticulum
Site of lipid and steroid ( choloesterol) synthesis, lipid metabolism and drug detoxification
Which organelle is this?
Smooth endoplasmic reticulum
What are the 3 cellular extensions
-cilia
-flagellum
-microvilli
What is a cilia
-each cilium is composed of nine pairs of microtubules surrounding a central pair.
-Coordinated movement creates a unidirectional current that propels substances across cell surfaces.
Which cellular extension is this?
Cilia
What is a flagellum
-Like cilium but longer
-e.g. in humans is the sperm cell and its function is to propel (move) the cell
Which cellular extension is this ?
Flagellum (sperm cell)
What is a microvilli and its function
-Tubular extensions of the plasma membrane; contain a bundle of actin filaments.
-It’s function is to increase SA for absorption
Which cellular extension is this
Microvilli
What are the three immune system cells?
-macrophage
-plasma cells
- B cells
What is a macrophage ?
-tissue based
-once they are activated, they kill pathogens
-secrete cytokines
-present antigens to T helper cells
Which immune system cell is this?
Macrophage
What is a plasma cell?
-they have eccentric nucleus
-they are differentiated from B cells
-they secrete antibodies
Which immune system cell is this ?
Plasma cell
What are B cells?
-develop in bone marrow
-have membrane bound antibody
-differenciate into plasma cells
Which immune system cell is this?
B cells
Name 4 cytoskeleton elements
-microtubules
-microfilaments
-centrioles
-intermediate filaments
What are microtubules and their function
Support the cell and give it shape.Involved in intracellular and cellular movements. Form centrioles and cilia and flagella, if present
Which cytoskeleton element is this?
Microtubules
What are the functions of microfilaments
Involved in muscle contraction and other types of intracellular movement, help from the cell’s cytoskeleton
Which cytoskeleton element is this
Microfilaments
What are centrioles?
As part of the centrosome, organise a microtubule network during mitosis (cell division) to form the spindle and asters. Form the bases of cilia and flagella
Which cytoskeleton element is this?
Centrioles
What are intermediate filaments?
The stable cytoskeletal elements; resist mechanical forces acting on the cell
Which cytoskeleton element is this?
Intermediate filaments
What is a tissue?
Collections of cells to perform a function
Cells with special functions
Name the three cells that connect body parts, form linings or transport gases
-epithelial cells
-fibroblasts
-erythrocytes
Name the two cells that move organs and body parts
-skeletal muscle cell
-smooth muscle cells
Name a cell that stores nutrients
Fat cell
Name a cell that fights disease
Macrophage
Name a cell that gathers info and controls body functions
Nerve cell
Name a cell of reproduction
Sperm
Endocrine cell
-Most enzymes are ……….. soluble, ………….. proteins
-enzymes function as …………. …………
-most enzymes are highly specific- ………….. only one substrate or one type of substrate
- water, globular
- biological catalysts
- recognise
Enzymes lower ……….. energies
Activation
What is activation energy ?
Minimum amount of energy that must be available to reactants for chemical reaction to occur.
How do enzymes function?
By forming a complex with the substrate that stabilises it and lowers the activation energy
Energy for reactions is provided by the hydrolysis of ….
ATP
What is the active site ?
the complicated folding forms “clefts” of a particular shape on the surface of the enzyme
What is meant by recognition?
the enzyme “recognises” a particular substrate that fits the shape of the active site
What is meant by intermolecular forces?
Forces between separate molecules that hold the substance together
Lock and key model
Induced fit model
Catalytic cycle of an enzyme
Enzymes activity depends on three things….
-interactions with other molecules
-enzyme structure ( changes in pH and temperature)
-conc of the enzyme and substrate
How is enzyme activity affected by interactions with other molecules?
-Can occur at active site or else where
On protein surface.
-Some interactions will inhibit, some will regulate
Explain the graph
- As pH increases / decreases above / below an optimum, rate of reaction decreases
-Enzymes denature - tertiary structure and active site change shape
-As hydrogen / ionic bonds break
-So active site no longer complementary
-So fewer E-S complexes form
Explain this graph
-more enzyme molecules means more likely a substrate molecule is to collide with one and form a enzyme substrate complex
-if amount of substrate is limited, there’s more than enough enzyme molecules so adding more enzyme has no further effect
Explain this graph
-more substrate molecules means a collision between substrate and enzyme is more likely and so more active sites will be occupied
-then all active sites become full so increase in substrate concentration has no further effect and its beyond saturation
Explain this graph
-At low temp., rate is slow :molecules have low speeds and do not collide much and don’t have enough energy to overcome activation energy
-0°C - 40°C, enzyme activity increases with increasing temp. Molecules move faster and collide more and greater proportion of collision have enough energy to overcome activation energy.
-Above 40°C, majority of enzymes in the human body denature!
Describe and explain the effect of concentration of competitive inhibitors on the rate of enzyme-controlled reactions
● As concentration of competitive inhibitor increases, rate of reaction decreases
-Similar shape to substrate
-Competes for / binds to / blocks active site
-So substrates can’t bind and fewer E-S complexes form
● Increasing substrate conc. reduces effect of inhibitors (dependent on relative concentrations of substrate and inhibitor)
Describe and explain the effect of concentration of non-competitive inhibitors on the rate of enzyme-controlled reactions
● As concentration of non-competitive inhibitor increases, rate of reaction decreases
- Binds to site other than the active site (allosteric site)
- Changes enzyme tertiary structure / active site shape
- So active site no longer complementary to substrate
- So substrates can’t bind so fewer E-S complexes form
● Increasing substrate conc. has no effect on rate of reaction as change to active site is permanent
