Cell structure Flashcards
Module 1
1
Q
How many fundamentally types of cell?
A
Two - Prokaryotic and Eukaryotic Cells
2
Q
Definition of cells
A
The smallest structural and functional unit of an organism, which is typically microscopic and consists of cytoplasm and a nucleus enclosed in a membrane
3
Q
Definition of Tissue
A
A level of organisation in multicellular organisms; it consists of a group of structurally and functionally similar cells and their intercellular material.
4
Q
Definition of Biochemical
A
Relating to the chemical processes and substances which occur within living organisms
5
Q
Definition of Electron Microscopy
A
A technique for obtaining high-resolution images of biological and non-biological specimens.
6
Q
Definition of Microbiology
A
The branch of science that deals with microorganisms
7
Q
Definition of Bacteria
A
A member of a large group of unicellular microorganisms which have cell walls but lack organelles and an organised nucleus.
8
Q
Definition of Membrane
A
A thin sheet of tissue or layer of cells acting as a boundary, lining, or partition in an organism.
9
Q
Definition of Cytoplasm
A
The material or protoplasm within a living cell, excluding the nucleus
10
Q
Definition of Cytosol
A
The aqueous component of the cytoplasm of a cell, within which various organelles and particles are suspended
11
Q
What are eukaryotes?
A
An organism consisting of a cell or cells in which the genetic material is DNA
12
Q
What are prokaryotes?
A
A microscopic single-celled organism which does not have a distinct nucleus.
13
Q
Taxonomy
A
The classification of something, especially organisms - Phân loại
14
Q
What types of Domain do Prokaryotes include?
A
Bacteria and Archaea
15
Q
Characteristics of prokaryotic cells?
A
- Usually unicellular and generally smaller and less complex than eukaryotic cells.
- The organelles of prokaryotic cells are not membrane-bound.
16
Q
Characteristics of eukaryotic cells?
A
- Contain membrane-bound organelles.
17
Q
What types of Domain do Eukaryotes include?
A
Eukarya - including protists, fungi, plants and animals.
18
Q
How many kingdoms are there?
A
Five - Eubacteria, Archaeabacteria, Protista, Plantae, Fungi, Animalia
19
Q
Which Kingdoms do Prokaryotes possess?
A
Bacteria - Archaea
20
Q
Which kingdom do Eukaryotes possess?
A
Protista - Plantae - Fungi - Animalia
21
Q
What is peptidoglycan?
A
- Peptidoglycan (murein) is a polymer made of sugar (polysaccharide) and amino acid
- Serve a structural role in the bacterial cell wall, giving structural strength, as well as counteracting the osmotic pressure of the cytoplasm.
- Dense peptidoglycan layer which is critical for maintaining cell form and withstanding high osmotic pressures.
22
Q
What are the properties of the cell wall of Bacteria Gram (+)?
A
- Thick cell wall (30 layers of peptidoglycan) -> which retains the dying colour.
- Monoderm - One layer
23
Q
What are the properties of the cell wall of Bacteria Gram (-) ?
A
- Thin peptidoglycan layer
- Diderms - two layers
24
Q
What is “Endosymbiotic theory”?
A
The theory states that some organelles in Eukaryotic cells were once prokaryotic microbes (Chloroplasts, Mitochondria).
25
Distinguish Prokaryotes and Eukaryotes.
- Prokaryotes:
+ Don't have membrane-bound organelles
+ Do not possess a nucleus, just nucleoid
+ Cell wall which protects Prokaryotes much better than Eukaryotes.
- Eukaryotes:
+ Include lots of membrane-bound organelles: mitochondria, Golgi apparatus, ...
+ Have nucleus, DNA packed into multiple chromosomes.
+ Some may have cell wall but not as effective as prokaryotes
26
Diseases caused by bacteria??
Tuberculosis - Ear infection - Food poisoning - Pneumonia - Strep Throat - Staph Infection
27
Where to find prokaryotic organism?
Can be found everywhere - even in extreme environments such as volcanoes.
28
What is the capsule of bacteria?
- The capsule in bacteria is the outer layer enclosed the cell wall of bacteria.
- The capsule protects the bacterial cell from damage, dehydration and engulfment by eukaryotic cells.
- It also helps the bacteria stick to surfaces, increase the virulence (ability to cause disease) of pathogenic bacteria.
29
Structure of a prokaryotic cell?
Prokaryotic flagellum - Food granule - Ribosomes - Pili - Chromosomes (nucleoid region) - Capsule or Slime layer - Cell wall - Cytoplasm - Plasmid (DNA) - Plasma membrane.
30
Plasmids
Small rings of double-stranded DNA
31
How can some prokaryotes move around?
Using a tail-like structure called flagellum
32
Which part of the structure of prokaryotes help to generate movement?
Pili - This is also involved in the transfer of DNA between organism => specialised pili that can attach to surfaces are called fimbriae.
33
Where are bacteria common in?
Bacteria are common in moist, low-salt environments of moderate temperature, where sunlight or organic compounds are plentiful, and inside or on plants and animals.
34
Why bacteria need little oxygen to survive?
Because they have many ways of extracting energy and fixing carbon.
- For example, they can obtain energy from sunlight (photosynthesis) or by reducing inorganic compounds such as sulfides or ferrous ions (chemosynthesis).
35
What is the function of bacteria in ecosystems?
- They break down many kinds of substances, including plant and animal remains and wastes.
- Bacteria also widely used in industry to manufacture foods, such as cheese and yoghurt and in medicine to produce antibiotics, drugs and even human insulin.
- Some bacteria can even break down oils and plastics, making them useful for pollution control.
36
Eukaryotes:
- They are much larger and more complex than prokaryotic cells.
- Eukaryotic cells have a cell (plasma) membrane that surrounds the cell's cytoplasm and internal (non-plasma) membranes that from specialised compartments within the cell.
37
Compare the size of prokaryotic cells and eukaryotic cells
- Prok: very small (0.1 to 5 micrometer)
- Euk: larger, with large variation in size (10 to 100 micrometer)
38
Compare the SA:V between prokaryotic cells and eukaryotic cells
- Prok:
+ Large SA:V ratio
+ Allows materials to diffuse in and out the cell rapidly
- Euk:
+ Smaller SA:V ratio
+ Results in slower diffusion
39
Compare the membrane-bound organelles of prokaryotic cells and eukaryotic cells
- Prok:
+ Absent, no membrane-bound organelles
- Euk:
+ Many organelles bound by membranes, forming an organised internal structure (such as mitochondria, Golgi bodies, endoplasmic reticulum,...)
40
Compare chromosomal DNA of prokaryotic cells and eukaryotic cells
- Prok:
+ A single circular chromosome and small circular DNA molecules called plasmids
+ Located in a region of cytoplasm called the nucleoid, lacking a membrane
- Euk:
+ Linear chromosomes
+ Located in the nucleus, which is separated from the cytoplasm by a double-layered membrane.
41
Compare number of ribosomes in prokaryotic cells and eukaryotic cells
- Prok: many tiny ribosomes scattered throughout the cytoplasm
- Euk: many ribosomes, either attached to the ER, or free in the cytoplasm
42
Compare cell membrane of prokaryotic cells and eukaryotic cells
- Prok:
+ Bilayer of phospholipid molecules enclosing the cytoplasm in bacteria
+ Phospholipids in archaea are different and sometimes fuse into a monolayer
- Euk:
+ Bilayer of phospholipid molecules enclosing the cytoplasm
43
Compare the cell wall between prokaryotic cells and eukaryotic cells
- Prok:
+ In bacteria, consists of a protein/carbohydrate compound called peptidoglycan
+ In archaea, the cell wall is composed of surface-layer proteins that form a rigid layer
- Euk:
+ Present in fungi, plants and some protists
+ Mainly made of carbohydrates: chitin in fungi and cellulose in plants
44
Compare the flagella between prokaryotic cells and eukaryotic cells
- Prok:
+ May have flagella to provide movement
+ Consists of three protein fibrils coiled in a helix and protruding through the cell membrane and wall.
- Euk:
+ May have flagella or cilia (fine hair-like projections) for motility (but not in fungi)
+ Consists of a highly organised array of microtubules (hollow protein tubes) enclosed by extended cell membrane
45
What is the function of Centrosome (Trung thể)?
- Only active during cell devisions
- Produce spindle fibers which attach to chromosome
46
What are non-membrane bound organelles?
- Ribosomes
- Cell wall
- Flagella
- Centriole
- Cytoskeleton
- Microvilli
47
What are membrane-bound organelles?
- Nucleus
- Mitochondria
- Endoplasmic reticulum
- Golgi apparatus
- Lysosomes
- Peroxisomes
- Vesicles
48
Benefits of compartmentalisation:
- Allowing enzymes and reactants for a particular cellular function to be close together in high concentrations and at the right conditions, such as at optimum pH levels so that the processes within the organelles are very efficient
- Allowing processes that require different environments to occur at the same time, in the same cell
- Making the cell less vulnerable to changes to its environment, because any changes will affect the cytosol much more than the membrane-bound organelles.
49
Describe the structure and Function of Nucleus.
- Structure:
+ Membrane-bound: double membrane
+ Contains DNA
- Function: contains the genetic instructions for cell replication, growth, repair and function.
50
Describe Describe the structure and Function of Ribosome
- Structure:
+ Made of proteins and rRNA
+ No membrane
- Function: synthesises proteins
51
Describe the structure and Function of Rough Endoplasmic reticulum
- Structure:
+ Membrane-bound networks of cisternae (membraneous sacs)
+ Ribosomes bind to its membranes, giving it a 'rough' appearance
- Function: processes and modifies proteins
52
Describe the structure and Function of Smooth Endoplasmic reticulum
- Structure: a membrane-bound network of cisternae
- Function: synthesises lipids
53
Describe the structure and Function of Golgi apparatus
- Structure: a membrane-bound stack of cisternae that are not connected to each other
- Function: processes and packages proteins
54
Describe the structure and Function of Lysosomes
- Structure: membrane-bound vesicle containing digestive enzymes.
- Function: digests cellular waste material and foreign matter
55
Describe the structure and Function of centriole
- Structure: small structure in the cytoplasm, consisting of microtubules
- Function: involved in cell division and the formation of cell structures such as flagella and cilia.
56
Describe the structure and Function of Mitochondria
- Structure:
+ Membrane-bound, double membrane, inner membrane is highly folded.
+ Contains DNA
- Function: obtains energy from organic compounds
57
Describe the structure and Function of Chloroplasts
- Structure:
+ Spherical or ellipsoidal, with double membrane
+ Contains DNA and thylakoid sác
- Function: use light energy, carbon dioxide and water to produce glucose
58
Describe the structure and Function of cilium or flagellum.
- Structure: external structure consisting of microtubules.
- Function: Motility: movement of substances across cell surface
59
Describe the structure and Function of Vacuole.
- Structure: membrane-bound, fluid-filled vesicle
- Function: stores substances; also involved in cell structure in plant cells
60
Describe the structure and Function of Plastid
- Structure:
+ Small, with double membrane
+ Contains DNA (occurs most in plants and algae)
- Function: Synthesises and stores various organic molecules
61
Describe the structure and Function of Cell wall.
- Structure:
+ External structure surrounding cell membrane
+ Composition depends on types of cell
+ No membrane
- Function: cell structure and protection
62
Listing organelles with the function of synthesising and processing of proteins and lipids.
- Nucleus
- Ribosomes
- Rough endoplasmic reticulum
- Smooth endoplasmic reticulum
- Golgi apparatus
- Lysosome
63
Listing organelles with the function of energy transformations.
- Mitochondria
- Chloroplasts
64
Listing organelles with the function of storage and cell structure.
- Vacuole
- Plastid
- Cell wall
- Cytoskeleton
- Centriole
- Cilium or Flagellum
65
Compare difference between vacuole in Plant cells and Animal cells.
- Plant cells: store water (90%), nutrients, also waste
- Animal cells: much smaller which is used to store, contains nutrients, waste and water.
66
What process occur in mitochondria?
Cellular respiration
67
What process occur in chloroplasts?
Photosynthesis
68
Describe characteristics of two layers of the mitochondria.
- The outer membrane gives the mitochondria their shape and allows passage of small substances into and out of the organelle.
- The inner membrane is folded into fine, finger like ridges, called cristae, increasing the surface area.
- The central space is filled with fluid called the matrix. It contains mitochondrial DNA and enzymes that give mitochondria the unusual feature of being able to replicate themselves.
69
Which organelles synthesis Lysosomes?
Golgi body
70
Compare type of connection between 2 cells in plant and animal cells
- Plant: Plasmodesmata
- Animal: Gap junction
71
What is nucleolus?
- It is the organelle within the nucleus which builds ribosomes.
72
What are Lysosomes?
Organelles which break larger molecules into smaller molecules so the cell can reuse them (membrane-bound organelle)
73
What are peroxisomes?
Organelles which remove toxic wastes (detoxification) from the cell to prevent them from poisoning the cell
74
Definition of plasmodesmata.
Openings in plant cells that allow cell products and nutrients to pass from cell to cell.
75
Endoplasmic reticulum serves as an internal delivery system for cell transporting materials the cell needs.
Informative sentence
76
What function is shared by mitochondria and chloroplasts?
Both mitochondria and chloroplast function to generate metabolic energy, evolved by endosymbiosis, contain their own genetic systems, and replicate by devision.
77
List the main differences between plant and animal cells.
Cell wall and chloroplasts
78
What are commonly regulated aspects of the internal environment?
- Temperature
- Oxygen concentration
- Carbon dioxide concentration
- pH
- Osmotic pressure
- Nitrogenous waste concentration
- Glucose concentration
79
What does the fluid mosaic model describe?
- The fluid mosaic model describes the cell membrane double layer of lipids, a phospholipid bilayer, with the ability to flow and change shape, like a two-dimensional fluid
- Specialised protein molecules are embedded in the lipid in various patterns like a mosaic.
- Both proteins and phospholipids help to control the exchange of materials between the external and internal environments.
80
Describe each phospholipid in the phospholipid bilayer.
- Each can be represented by a head and two tails:
+ A phosphate group on the head makes this end hydrophilic (water loving)
+ The fatty acid tails are hydrophobic (water hating)
- When these two molecules form a bilayer
- The water-attracting heads are positioned facing outwards - towards the cytoplasm on one side and to the outside of the cell on the other side.
- The water-repelling tails are positioned inwards - towards each other. It is not rigid in structure (fluid)
81
Which components of cell membrane make it more flexible.
- Cholesterol makes the membrane more flexible
- Membrane flexibility in plants is increased by a different lipid - phytosterol.
82
What are common function of membrane proteins?
- These proteins enable cell-to-cell interaction and communication, and the exchange of substances between the cell and the external environment.
83
Function of transport proteins
They act like passageways that allow specific substances to move across the membrane
84
Function of membrane proteins
Involved in cellular communication
85
Function of Receptor proteins
- They are different in different types of cells.
- They cause the cells to respond only to certain signals from substances such as hormones that bind them, giving them specific functions.
86
What are glycoproteins?
- They are membrane recognition proteins which are made up of a protein molecule with a carbohydrate molecule attached.
87
Function of cell membrane
- It acts as a barrier that keeps foreign substances outside of the cell.
- The cell membrane is selectively permeable. It selects what can pass or permeate into and out of the cell.
- It is also involved in cell signalling and communication.
87
Function of glycoproteins
- These proteins identify the cell and are called antigens or marker molecules.
- They allow immune system to distinguish between foreign particles and the body's own cells. This ensures that immune system will destroy only foreign particles that display "non-self" markers.
88
Describe embedded proteins
- These proteins span (mở rộng) the entire bilayer
- These proteins are also called INTEGRAL or TRANSMEMBRANE proteins
+ Transmembrane proteins form channels, pumps, and receptors. (Some proteins are found in only the inner or outer of the phospholipid bilayer)
+ Peripheral proteins can be enzymes or hormones that help with cell signalling or catalyse reactions within a cell.
88
Function of glycolipids
- Maintain membrane stability
- Facilities cell-cell communication acting as receptors, anchors for protein and regulations of signal transduction.
88
Function of protein channel
- Facilitates the transport of substances across a cell membrane (through diffusion, or active transport) depending on concentration gradient
88
What are types of transport through cell membrane?
Diffusion - Active transport - Endocytosis - Exocytosis
89
Explain why models are used in science and how they are validated.
Because it helps scientists and students easily understand how processes operate in the cell, and how particles move in and out of the cells in order to provide significant knowledge to operate future experiments or applications
89
Function of protein carrier
- Move molecules across the membrane, thus facilitating membrane transport but energy is required here.
- Protein carriers facilitate the transport of ions or molecules across the membrane, often against a concentration gradient, using energy from ATP or existing gradients, ensuring selective and efficient transport.
90
Explain the structure of a lipid bilayer
A lipid bilayer consists of a continuous double layer of lipid molecules in which membrane proteins are embedded.
91
What is light microscope? (magnification, resolution, advantages, disadvantages, and how image is produced)
- Magnification: up to 1500x (depends on lenses used)
- Resolution: greater than or equal to 200 nm
- Function: magnify small objects (eg. cells and microorganisms), allow scientists and researchers to observe the structure, shape, and sometimes the movement of microscopic entities in detail
- Advantages: can view both living and non-living specimens, natural colour images, cost-effective
- Disadvantages: cannot observe 2 objects having distance < 200 nm due to the use of light ( resolution is limited due to the wavelength of visible light)
- How image is produced: pass light rays through thin specimens or stained cells that are magnified by convex glass lenses.
92
What is a fluorescent microscope? (magnification, resolution, advantages, disadvantages, and how image is produced)
- Magnification: up to 1500x
- Resolution: greater than or equal to 200 nm
- Function: visualize specific components of a specimen with high sensitivity and specificity, which can be tagged to antibodies, proteins, or other molecules within cells, allowing researchers to highlight and study particular structures like organelles, proteins, or even single molecules within a complex environment.
- Advantages: view both living and non-living specimens, high sensitivity (độ nhạy cao), multicolour-imaging, 3D imaging capabilities
- Disadvantages: cannot observe 2 objects have distance < 200nm, high cost, complex sample preparation, ...
- How image is produced:
+ Fluorescent substance that will attach to the structures that scientists want to specifically observe.
+ High-intensity light that causes the fluorescent substance to emit light and the image is produced.
93
Describe Transmission Electron Microscope (TEM)
- Magnification: 1.5 million X
- Resolution: 2nm (because beam of electrons have a much shorter wavelength than light)
- Advantages:
+ High resolution, high magnification -> can observe sub-cellular level
+ Observe materials that were formerly believed to have little or no structure have to be shown to have elaborate internal organisation.
- Disadvantages:
+ High cost
+ Sample preparation
+ Specimens must be placed in a vacuum for viewing and these must be death
+ 2D imaging
- How image is produced:
+ Usage of electron beam instead of light
+ Electrons are transmitted the specimen
+ Produces a 2D image
94
Outline parts of a light microscope.
The light microscope possesses:
- Eyepiece (ocular lens)
- Revolving nosepiece
- Objective lens
- Stage clips
- Stage
- Condenser lens
- Iris diaphragm
- Light source
- Fine focus knob (moving the objectve lens slightly to make the image clearer)
- Coarse focus knob (move the stage up and down)
95
Describe Scanning Electron Microscope (SEM) (magnification, resolution, advantages, disadvantages, and how image is produced)
- Magnification: nearly 1 million X
- Resolution: 10nm
- Advantages: high resolution, 3D Imaging, Depth of FOV, Surface composition analysis
- Disadvantages: conductive layer sample preparations, high cost, vacuum requirement
- How image is produced: scanning a focused electron beam across a sample's surface, detecting emitted signals like secondary and backscattered electrons, and producing high-resolution, detailed surface images.
96
Describe Confocal Laser Scanning Microscopy (magnification, resolution, advantages, disadvantages, and how image is produced)
- Magnification: up to 17280x
- Resolution: 250 nm
- Advantages:
+ Optical sectioning capability, resolutions and versatility with 3D imaging
+ Provide multi-color imaging, ability to adjust the pinhjole size to set the optical section thickness
- Disadvantages:
+ Expensive,
+ Limited number of excitaion wavelength available with common lasers
+ Harmful nature of high-intensity laser
- How image is produced:
+ The illumination and detection optics are focused on the same diffraction - limited spot in the sample which is the only spot imaged by the detector during a confocal scan
+ To generate a complete image, the spot must be moved over the sample and data collected point by point.
97
