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Human Sciences I ( Year 0) > Cells And Enzymes > Flashcards

Cells And Enzymes Flashcards

1
Q

What is the three dimensional structure of a eukaryotic cell maintained by and what does it consist of

A

-cytoskeleton
-consists of interconnected protein filaments in the cytoplasm

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2
Q

What is the pH of the cytoplasm

A

7.2

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3
Q

What is the pH in extracellular fluid

A

7.4

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4
Q

What is the average diameter of a cell

A

10-20 microns

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5
Q

Why is it useful to use red blood cells to measure other cells

A

-have a diameter of 7 microns and are considered the smallest cells

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6
Q

Primary structure of a cell membrane is made up of ………….

A

Phospholipids

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7
Q

Phospholipids have a ……….. head and …………… tails

A

1.hydrophilic
2.hydrophobic

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8
Q

Why does health of the individual depend on the normal functioning of cells in the body

A

-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

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9
Q

What happens when you shake water and phospholipids together

A

Forms a micelle

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10
Q

what are the membrane components and how do they affect movement of substances across cell membranes

A

*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

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11
Q

Function of a nucleus

A

-Control centre of the cell
-responsible for transmitting genetic information and providing the instructions for protein synthesis

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12
Q

What is this organelle?

A

Nucleus

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13
Q

What is the function of ribosomes

A

-Protein synthesis- a place where mRNA is translated into protein.
-It contains rRNA and proteins

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14
Q

Which organelle is this ?

A

Ribosomes

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15
Q

What is the rough endoplasmic reticulum and its function

A

-Sugar groups are attached to proteins within the cisterns.
-Proteins are bound in vesicles for transport to the golgi apparatus and other sites.

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16
Q

Which organelle is this

A

Rough endoplasmic reticulum

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17
Q

What is the function of mitochondria

A

-Site of ATP synthesis; powerhouse of the cell.
-Energy production through aerobic metabolism and Ketogenesis

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18
Q

What is ketogenesis

A

A metabolic pathway that produces ketone bodies which provide an alternative form of energy for the body

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19
Q

Which organelle is this

A

Mitochondria

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20
Q

What is the Golgi apparatus and its function

A

-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

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21
Q

Which organelle is this ?

A

Golgi apparatus

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22
Q

What are lysosomes and what are their functions

A

-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

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23
Q

Which organelle is this?

A

Lysosomes

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24
Q

What is the function of the smooth endoplasmic reticulum

A

Site of lipid and steroid ( choloesterol) synthesis, lipid metabolism and drug detoxification

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25
Which organelle is this?
Smooth endoplasmic reticulum
26
What are the 3 cellular extensions
-cilia -flagellum -microvilli
27
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.
28
Which cellular extension is this?
Cilia
29
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
30
Which cellular extension is this ?
Flagellum (sperm cell)
31
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
32
Which cellular extension is this
Microvilli
33
What are the three immune system cells?
-macrophage -plasma cells - B cells
34
What is a macrophage ?
-tissue based -once they are activated, they kill pathogens -secrete cytokines -present antigens to T helper cells
35
Which immune system cell is this?
Macrophage
36
What is a plasma cell?
-they have eccentric nucleus -they are differentiated from B cells -they secrete antibodies
37
Which immune system cell is this ?
Plasma cell
38
What are B cells?
-develop in bone marrow -have membrane bound antibody -differenciate into plasma cells
39
Which immune system cell is this?
B cells
40
Name 4 cytoskeleton elements
-microtubules -microfilaments -centrioles -intermediate filaments
41
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
42
Which cytoskeleton element is this?
Microtubules
43
What are the functions of microfilaments
Involved in muscle contraction and other types of intracellular movement, help from the cell’s cytoskeleton
44
Which cytoskeleton element is this
Microfilaments
45
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
46
Which cytoskeleton element is this?
Centrioles
47
What are intermediate filaments?
The stable cytoskeletal elements; resist mechanical forces acting on the cell
48
Which cytoskeleton element is this?
Intermediate filaments
49
What is a tissue?
Collections of cells to perform a function
50
51
Cells with special functions
52
Name the three cells that connect body parts, form linings or transport gases
-epithelial cells -fibroblasts -erythrocytes
53
Name the two cells that move organs and body parts
-skeletal muscle cell -smooth muscle cells
54
Name a cell that stores nutrients
Fat cell
55
Name a cell that fights disease
Macrophage
56
Name a cell that gathers info and controls body functions
Nerve cell
57
Name a cell of reproduction
Sperm
58
Endocrine cell
59
-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
60
Enzymes lower ……….. energies
Activation
61
What is activation energy ?
Minimum amount of energy that must be available to reactants for chemical reaction to occur.
62
How do enzymes function?
By forming a complex with the substrate that stabilises it and lowers the activation energy
63
Energy for reactions is provided by the hydrolysis of ….
ATP
64
65
66
What is the active site ?
the complicated folding forms “clefts” of a particular shape on the surface of the enzyme
67
What is meant by recognition?
the enzyme “recognises” a particular substrate that fits the shape of the active site
68
What is meant by intermolecular forces?
Forces between separate molecules that hold the substance together
69
Lock and key model
70
Induced fit model
71
Catalytic cycle of an enzyme
72
Enzymes activity depends on three things….
-interactions with other molecules -enzyme structure ( changes in pH and temperature) -conc of the enzyme and substrate
73
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
74
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
75
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
76
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
77
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!
78
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)
79
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

Human Sciences I ( Year 0) (10 decks)

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