Cellular Structure and Function Chp 2 Flashcards
(91 cards)
1
Q
What are the two fundamental classifications of organisms?
A
Prokaryotes and Eukaryotes
2
Q
What does the cell theory state?
A
Cells are the basic structural units of all living things; all cells arise from pre-existing cells; all living organisms are composed of one or more cells.
3
Q
Define Biogenesis in relation to cell theory.
A
Biogenesis is the principle that living organisms arise from pre-existing life, supporting the idea that cells come from other cells.
4
Q
Explain the concept of spontaneous generation.
A
Spontaneous generation is the discredited hypothesis that living organisms can arise from non-living matter.
5
Q
List common features shared by all cells.
A
- Cell membrane
- Cytoplasm
- Genetic material (DNA)
- Ribosomes
6
Q
What are the general features of prokaryotic cells?
A
- Lack membrane-bound organelles
- Generally smaller than eukaryotic cells
- Circular DNA
- Binary fission reproduction
7
Q
Summarise the key features of bacteria.
A
- Unicellular
- Prokaryotic
- Can be pathogenic or beneficial
- Diverse metabolic pathways
8
Q
What is murein and where is it found?
A
Murein is a polymer that forms the cell wall of most bacteria, providing structural support.
9
Q
What is the significant difference between Gram-positive and Gram-negative bacteria?
A
Gram-positive bacteria have a thick murein layer, while Gram-negative bacteria have a thin murein layer and an outer membrane.
10
Q
Define an extremophile.
A
An extremophile is an organism that thrives in extreme environmental conditions.
11
Q
Describe the environments of thermophiles.
A
Thermophiles thrive in high-temperature environments, such as hot springs.
12
Q
Describe the environments of cryophiles.
A
Cryophiles thrive in extremely cold environments, such as polar ice.
13
Q
Describe the environments of acidophiles.
A
Acidophiles thrive in acidic environments, such as acid mine drainage.
14
Q
Describe the environments of halophiles.
A
Halophiles thrive in high-salt environments, such as salt lakes.
15
Q
Describe the environments of xerophiles.
A
Xerophiles thrive in extremely dry environments, such as deserts.
16
Q
List other environments where extremophiles might be found.
A
- Deep-sea vents
- Alkaline lakes
- Hot springs
- High-radiation areas
17
Q
What is a significant feature of eukaryotic cells compared to prokaryotic cells?
A
Eukaryotic cells have membrane-bound organelles.
18
Q
What do cells need to exchange with their environment?
A
Nutrients, waste products, gases, and signals
19
Q
How do cells increase the efficacy of exchange with their environment?
A
By increasing surface area relative to volume
20
Q
What can cells increase in order to increase in size?
A
Cell volume
21
Q
What are the three ways a cell can increase the membrane surface area without changing cell volume?
A
- Folding of the membrane
- Formation of microvilli
- Development of invaginations
22
Q
A
23
Q
Describe the difference between the plasma membrane and the internal membranes found within the cell.
A
The plasma membrane encloses the cell, while internal membranes compartmentalize organelles.
24
Q
Define: Cell compartmentalisation
A
The division of a cell into distinct compartments, each with specific functions.
25
Define: Organelle
A specialized subunit within a cell that has a specific function.
26
State the role of organelle membranes.
To separate the organelle's contents from the cytoplasm and regulate the passage of materials.
27
List the benefits of compartmentalisation.
* Allows for specialized environments
* Increases efficiency of cellular processes
* Protects cellular components from harmful reactions
28
Explain the difference between a membrane-bound and non-membrane-bound organelle.
Membrane-bound organelles are enclosed by membranes, while non-membrane-bound organelles are not.
29
What type of organelle would you expect to find in prokaryotic cells?
Non-membrane-bound organelles.
30
What type of organelle would you expect to find in eukaryotic cells?
Membrane-bound organelles.
31
List the three main functions of cell organelles.
* Energy transformation
* Synthesis of molecules
* Storage and transport
32
Which organelles are only found in plant cells?
* Chloroplasts
* Cell wall
* Plastids
33
Which organelles are only found in animal cells?
* Lysosomes
* Centrioles
34
Detail the importance of energy transformations in cells.
Energy transformations are crucial for cellular processes, and the two main organelles involved are mitochondria and chloroplasts.
35
36
What is the Endosymbiotic theory?
A theory that explains the origin of eukaryotic cells from prokaryotic organisms.
## Footnote
This theory suggests that certain organelles, like mitochondria and chloroplasts, originated as free-living bacteria that were engulfed by ancestral eukaryotic cells.
37
What is the role of vacuoles in terms of storage and structure?
Vacuoles serve as storage spaces for substances such as nutrients, waste products, and water, and help maintain cell structure.
## Footnote
Vacuoles are larger in plant cells and play a key role in turgor pressure.
38
What is the role of plastids in terms of storage and structure?
Plastids are organelles involved in the storage of products like starch and pigments, and play a role in photosynthesis.
## Footnote
Examples include chloroplasts, which contain chlorophyll.
39
What is the composition of cell walls found in plant cells?
Cell walls in plant cells are primarily composed of cellulose.
## Footnote
Cellulose provides structural support and rigidity to plant cells.
40
What is the composition of cell walls found in fungal cells?
Cell walls in fungal cells are primarily composed of chitin.
## Footnote
Chitin provides structural strength to fungal cell walls.
41
What is the composition of cell walls found in prokaryotic cells?
Cell walls in prokaryotic cells are primarily composed of peptidoglycan.
## Footnote
Peptidoglycan provides structural integrity to bacterial cell walls.
42
What is the role of the cytoskeleton?
The cytoskeleton provides structural support, facilitates cell movement, and helps transport materials within the cell.
## Footnote
It consists of microfilaments, intermediate filaments, and microtubules.
43
What are centrioles?
Centrioles are cylindrical structures involved in cell division and the formation of cilia and flagella.
## Footnote
They are composed of microtubules arranged in a specific pattern.
44
What are cilia and flagella?
Cilia and flagella are hair-like structures that aid in cell movement and the movement of substances across the cell surface.
## Footnote
They have a similar structure but differ in length and number.
45
List the main differences between plant and animal cells.
1. Plant cells have a cell wall; animal cells do not.
2. Plant cells contain chloroplasts; animal cells do not.
3. Plant cells have larger vacuoles; animal cells have smaller ones.
4. Animal cells have centrioles; plant cells typically do not.
46
Define extracellular fluid.
Fluid found outside of cells that provides a medium for cellular exchange.
## Footnote
It includes interstitial fluid and plasma.
47
Define intracellular fluid.
Fluid found inside cells that contains various organelles and is essential for cellular processes.
## Footnote
It comprises cytosol and organelle fluids.
48
Define the external environment.
The environment outside the cell that interacts with the plasma membrane.
## Footnote
It includes all external factors affecting the cell's function.
49
Define the internal environment.
The environment inside the cell, including the cytoplasm and organelles.
## Footnote
It is regulated for optimal cellular function.
50
List some commonly regulated aspects of the internal environment.
* pH
* Temperature
* Ion concentrations
* Nutrient levels
51
What is the role of the plasma membrane?
The plasma membrane regulates interactions between the cell and its extracellular fluid, controlling the entry and exit of substances.
## Footnote
It maintains homeostasis and facilitates communication.
52
Define the fluid mosaic model.
A model that describes the plasma membrane as a dynamic structure with various proteins embedded in or associated with a fluid lipid bilayer.
## Footnote
It emphasizes the flexibility and diversity of membrane components.
53
What are phospholipids?
Molecules that make up the lipid bilayer of the plasma membrane, consisting of a hydrophilic 'head' and two hydrophobic 'tails'.
## Footnote
Their arrangement is crucial for membrane structure and function.
54
Explain why the phospholipid layer is arranged the way it is.
The hydrophilic heads face outward towards the aqueous environments, while the hydrophobic tails face inward, away from water, forming a bilayer.
## Footnote
This arrangement is essential for membrane integrity and function.
55
Describe the chemical nature of a cholesterol molecule.
Cholesterol is a lipid that is hydrophobic and helps to maintain membrane fluidity and stability.
## Footnote
It prevents the membrane from becoming too rigid or too fluid.
56
What is the role of cholesterol in the plasma membrane?
Cholesterol modulates membrane fluidity and permeability, helping to stabilize the membrane structure.
## Footnote
It is particularly important at varying temperatures.
57
Explain the difference between an integral protein and a peripheral protein.
Integral proteins span the membrane and are embedded within the lipid bilayer, while peripheral proteins are attached to the exterior or interior surfaces of the membrane.
## Footnote
Integral proteins often function as channels or transporters.
58
When is an integral protein referred to as a transmembrane protein?
An integral protein is referred to as a transmembrane protein when it extends across the entire lipid bilayer.
## Footnote
These proteins often facilitate transport across the membrane.
59
List the various roles of transmembrane proteins in a cell.
a) Transport of substances
b) Reception of signals
c) Cell recognition
d) Cell adhesion
e) Enzymatic activity
f) Structural support
60
What are the components of a glycoprotein?
Glycoproteins consist of proteins with carbohydrate chains attached.
## Footnote
They play roles in cell recognition and signaling.
61
What are the components of a glycolipid?
Glycolipids consist of lipids with carbohydrate chains attached.
## Footnote
They contribute to cell membrane stability and recognition.
62
Why is the plasma membrane described as a semi-permeable membrane?
The plasma membrane allows certain substances to pass while restricting others, maintaining homeostasis.
## Footnote
This selectivity is crucial for cell function.
63
Define diffusion.
The process by which molecules move from an area of higher concentration to an area of lower concentration.
## Footnote
It is a fundamental mechanism for substance movement across membranes.
64
Define solute.
A substance that is dissolved in a solvent to form a solution.
## Footnote
Examples include salts and sugars.
65
Define solvent.
A substance that dissolves a solute to form a solution.
## Footnote
Water is the most common solvent in biological systems.
66
Define solution.
A homogeneous mixture of a solute dissolved in a solvent.
## Footnote
Solutions are crucial for cellular processes.
67
Define concentration gradient.
A difference in the concentration of a substance across a space.
## Footnote
It drives diffusion processes.
68
Define passive transport.
The movement of substances across a membrane without the use of energy.
## Footnote
It occurs along the concentration gradient.
69
Define simple diffusion.
The direct movement of small, uncharged molecules across the plasma membrane without assistance.
## Footnote
Examples include oxygen and carbon dioxide.
70
Define facilitated diffusion.
The process by which specific molecules are transported across a membrane via protein channels or carriers.
## Footnote
It does not require energy and occurs down the concentration gradient.
71
Define competitive inhibition.
A process where a molecule competes with a substrate for binding to an enzyme's active site, reducing the enzyme's activity.
## Footnote
It is a common mechanism of enzyme regulation.
72
Define channel proteins.
Proteins that form pores in the membrane, allowing specific ions or molecules to pass through.
## Footnote
They facilitate facilitated diffusion.
73
Define carrier proteins.
Proteins that bind to specific molecules and change shape to transport them across the membrane.
## Footnote
They are involved in both facilitated diffusion and active transport.
74
What are the three main factors that affect the rate of diffusion?
* Concentration
* Temperature
* Particle size
75
Define osmosis.
The diffusion of water across a semi-permeable membrane from an area of lower solute concentration to an area of higher solute concentration.
## Footnote
It is a vital process for maintaining cell turgor.
76
Explain the difference between the osmotic gradient and osmotic pressure.
The osmotic gradient refers to the difference in solute concentration across a membrane, while osmotic pressure is the pressure required to prevent water movement across that membrane.
## Footnote
Osmotic pressure is critical in determining the direction of water movement.
77
78
Define hypertonic solutions.
A hypertonic solution has a higher solute concentration compared to another solution.
## Footnote
Example: Seawater is hypertonic to human cells, causing them to lose water.
79
Define isotonic solutions.
An isotonic solution has the same solute concentration as another solution.
## Footnote
Example: Normal saline is isotonic to human blood.
80
Define hypotonic solutions.
A hypotonic solution has a lower solute concentration compared to another solution.
## Footnote
Example: Pure water is hypotonic to human cells, causing them to swell.
81
What is active transport?
Active transport is the movement of molecules across a membrane against their concentration gradient, requiring energy.
## Footnote
Example: Sodium-potassium pump.
82
What are the two significant differences between active and passive transport?
* Active transport requires energy
* Passive transport does not require energy
83
What properties do active transport and facilitated diffusion share?
Both processes involve transport proteins to move molecules across cell membranes.
## Footnote
Example: Glucose transporters are used in both processes.
84
What are the key differences between active transport and facilitated diffusion?
* Active transport moves substances against their concentration gradient
* Facilitated diffusion moves substances down their concentration gradient
85
How does glucose transport illustrate the role of facilitated diffusion and active transport?
Glucose enters cells through facilitated diffusion and is then actively transported for energy use.
## Footnote
Glucose uptake is essential for energy production in all cells.
86
What types of molecules are moved by bulk transport?
* Large molecules
* Particles
* Groups of molecules
87
Is bulk transport a passive or active process?
Bulk transport is an active process.
88
Define exocytosis.
Exocytosis is the process by which a cell expels materials in vesicles that fuse with the plasma membrane.
89
Define endocytosis.
Endocytosis is the process by which a cell engulfs materials from the outside environment.
90
Define phagocytosis.
Phagocytosis is a type of endocytosis where large particles or cells are engulfed by the cell.
91
Define pinocytosis.
Pinocytosis is a type of endocytosis where the cell engulfs liquid and dissolved substances.
