Module One: 2. Cell Structure and technologies Flashcards
- Investigate a different cellular structures, including but not limted to: - examining a variety of prokaryotic and eukaryotic cells (ACSBL032, ACBL048) - describe a range of technologies that are used to determine a cell's structure and function.
1
Q
What are the 2 main domains of Prokaryotes?
A
- Bacteria
- Archea
2
Q
What are eukaryotes? between what sizes do they vary from?
A
- Eukaryotes are living organisms that contain eukaryotic cells. 10- 100 micrometres
( Multicellular plants and animals are composed of a variety of different types of eukaryotic celld)
3
Q
What are prokaryotes? between what sizes do they vary from?
A
0.1 to 5.0 micrometres
4
Q
Summarize the difference in Prokaryotic and eukaryotes?
A
- Both Bacteria and archea lack a nucleus or other membrane bound organelles, the archae are more closely reated to eukaryotes than they are to bacteria.
- The archae and bacteria diverged 3.7 billion years ago. Archae and eukarya diverged 1.2 billion years ago.
- ( first evidence of life is found to be 4.2 billion years ago)
5
Q
Compare and contrast the differences and similarities of prokaryotes and eukaryotes?
A
Compare and contrast the differences and similarities of prokaryotes and eukaryotes?
6
Q
Summarize Prokaryote structures?
A
- Prokaryotes also vary in terms of structures they possess.
- The generalised structure of a prokaryote:
All prokaryotes have a cell memebrane, a cell wall made of peptidoglycan, cytoplasm, ribosomes and a single circular chromosome which can be observed a s a nucleoid. - Many prokaryotes also have flagellum, pilli and plasmids.
7
Q
Explain the structure and the function of peptidoglycan?
A
Made of NAG (N-acetylglucosamine) and NAM (N-acetylmuramic acid) sugars.
Forms a mesh-like layer around bacterial cells.
Peptide chains cross-link the sugar chains, providing strength.
Gives bacteria their shape and structural support.
Protects bacteria from osmotic pressure and mechanical damage.
Targeted by antibiotics like penicillin, which weakens the cell wall.
8
Q
Explain the structure and function of cytoplasm?
A
Cytoplasm is fluid material where activities of the cell occur
9
Q
Explain the structure and function of ribosomes?
A
Ribosomes are small organelles in cells, composed of RNA and protein, responsible for synthesis of proteins. They carry out DNA instructions and form polypeptides. Ribosomes can be found in the cytoplasm or scattered over the ER surface.
10
Q
Why is there no membrane surrounding genetic material?
A
11
Q
What is bacterial chromosome?
A
A bacterial chromosome is a single, circular, double-stranded DNA molecule that contains the majority of a bacterium’s genetic information, organized into a structure called the nucleoid, and is not enclosed in a nucleus like in eukaryotic cells.
12
Q
What does pilli do?(pilus)
A
Pili, hair-like appendages on bacteria, primarily function in adhesion to surfaces, facilitating bacterial colonization and infection, and also play a role in DNA transfer and motility
13
Q
What does Flagella help a cell do? cell wall?
A
1/ Flagella are whip-like structures that enable cells to move, acting as a kind of propeller or motor, allowing them to swim through liquids or move across surfaces.
2/ The cell wall provides structural support, shape, and protection to the cell, acting as a barrier against external forces and maintaining cell integrit
14
Q
What does capsule layer composed of?
A
A bacterial capsule layer, a protective structure outside the cell wall, is primarily composed of polysaccharides (simple sugar polymers), though some exceptions exist, like Bacillus anthracis which has a capsule made of poly-D-glutamic acid.
15
Q
What is unicellular? Plasmid?
A
16
Q
What type of cell does the earth consist more of?
A
prokaryotic cells
17
Q
What are eukaryotic cells? name 5 points?
A
- ## Eukaryotic cells are characterised by a membrane bound and are known as organelles.
18
Q
What are organelles?
A
- Organelle performs a specific function within the cell.
- Together these organelles carry out all of the biochemical processes and reactions( such as photosynthesis and respiration)
19
Q
What distinguishes one cell from another?
A
Cellular structures and functions
Investigate cellular structures, including prokaryotic and eukaryotic cells.
20
Q
What are eukaryotes?
A
Organisms with a distinct membrane-bound nucleus and organelles
Includes animals, plants, fungi, and algae.
21
Q
List examples of eukaryotic organisms.
A
- Animals
- Plants
- Fungi
- Algae
22
Q
What is a key characteristic of multicellular eukaryotes?
A
Cell specialization
Allows for a variety of cell types and structures.
23
Q
What structures are unique to plant cells?
A
- Large vacuole
- Cellulose cell wall
- Plastids (including chloroplasts)
24
Q
What structure is typically absent in plant cells but present in animal and fungal cells?
A
Centrioles
25
What is the composition of fungal cell walls?
Chitin
26
True or False: All plant cells have chloroplasts.
True
27
Fill in the blank: _______ are typically absent in plant cells.
Centrioles
28
How does multicellularity benefit organisms?
Allows for cell specialization
29
What is the significance of cellular variety in multicellular eukaryotes?
Enables a large variety of cell types and structures within a single organism
30
What technologies are used to determine a cell’s structure and function?
Microbiological technologies
## Footnote
Includes various methods for examining cellular structures.
31
Which type of cell contains a large vacuole?
Plant cell
32
What distinguishes eukaryotic cells from prokaryotic cells?
Presence of a membrane-bound nucleus and organelles
33
List the main types of eukaryotic cells.
* Plant cells
* Animal cells
* Fungal cells
34
Describe the structure and function nucleus ?
- The nucleus is a large organelle bounded by a double membrane. It contains most of the cell's DNA, which allows it to control the activities of the cell by determining which proteins will be synthesised at the ribosomes.
35
Desctibe the structure and function of Nucleolus?
The nucleolus is a dark area that can be observed within the nucleus. It is the place in the nucleus where the Ribosomal RNA is synthesized
36
What are ribosomes?
They are not membrane bound organelles. However, they are very important cell strucutre. there made ribosomal RNA and protein.
- The ribosomes are the site of protein synthesis in the cell.
37
What is RNA?
ribonucleic acid, a nucleic acid present in all living cells. Its principal role is to act as a messenger carrying instructions from DNA for controlling the synthesis of proteins, although in some viruses RNA rather than DNA carries the genetic information.
38
What is structure and function of the Endoplasmic reticulum.?(ER)
- Endoplasmic reticula are network of membrane-bound sacs.
- Their function is allowing materials to be transported throughout the cell.
39
What are the 2 kinds of endoplasmic reticulum?
- Rough ER is involved in transporting proteins.
- Smooth ER is involved in transport of other compounds such as lipids.
40
What is mitochondria? part of the mitochondira.
- Mitochondria are organelles which are surrounded by two layers of memebrane.
parts : - Outer membrane
- Inner membrane
- Cristae
41
What is cristae?
42
What is Golgi apparatus?
The golgi appartus(body/complex) is a stack of flattened sacs which bud off into vesicles.
Their function is to modify complex is to modify proteins and package them for export from the cell.
43
who found about the golgi complex?
44
What is centriole?
each of a pair of minute cylindrical organelles near the nucleus in animal cells, involved in the development of spindle fibres in cell division.
45
What is cilia? flagella?
Cilia and flagella are protuberances from the cell membrane. Flagella are longer than cilia but have a similar structure. They are not really organelles as they do not comprise a cellular compartment.
Cilia and flagella contain protein fibres that move relative to each other to allow the structure to move.('wave'). Thus, this allows cillia and flagella for locomotion of the cell, or for moving fluids across the cell surface in multicellular organisms.
46
What is chloroplasts?
- Chloroplasts are large organelles bound by two layers of membrane. The outer layer surrounds the chloroplast are smaller structures called thylakoids, each also surrounded by a membrane of its own.
- Chloroplasts contain chlorophyll and are site of photosynthesis in plant cells.
47
What s granum? What do we call the space between grana?
- are stack like structures made of thylakoids. (grana stack of thylakoid disks)
- Stoma between the grana within the outer membrane.
48
Which two organelles in eukaryotes have their own DNA?
- Chloroplasts
- Mitochondria. ( The Dna is a single circular chromosome)
49
What is Fluid mosaic model?
- The Fluid mosaic model represents our current understanding of the structure of the structure of the cell membrane. It suggests that the membrane is composed of a bi-layer of phospholipids, in which proteins and other molecules are suspended.
50
What does the fluid mosaic model of a cell membrane suggest?
- It suggests that the membrane is composed of a bi-layer of phospholipids, in which proteins and other molecules are suspended. The fatty acid tail of phospholipids repel water. In this way, the membrane separates the cell's cytoplasm from the internal environment of the cell. Materials that are needed by the cell, or wastes that must be removed, are able to cross the membrane via trans membrane proteins.
( It's the idea of a bilayer of phospholipids,a double layer of phospholpids, that separates the fluid inside the cell from the fluid outside the cell)
51
What is a scientific model?
52
What did scientist of 1500s use to investigate organisms?
Scientists in the 1500s used handheld magnifying glasses to view objects of interest.
53
How was the first compund microscope made?
This microscope had two convex lenses placed at either end of a barrel and was the precursor to the light microscope.
54
What was the main improvement in the first compound microscope compared to handheld magnifying glasses?
The first compound microscope had two convex lenses placed at either end of a barrel, allowing for greater magnification.
This microscope had two convex lenses placed at either end of a barrel and was the precursor to the light microscope.
55
How did further developments in compound microscopes help scientists?
Improvements such as adding a stand, focus knobs, and a light source allowed scientists to better determine the structure of organisms.
56
Who first used the term ‘cella’ and what did it lead to?
Robert Hooke first used the term ‘cella’ in the 1660s when observing cork structure, which led to the modern term ‘cell’.
57
What are the 3 types of mordern microscopes?
- Light microscope.
- Fluorescence microscope.
- Electron microscope.
58
How does light microscopes work?
Compound Light Microscope Overview
* Light source passes through condenser lens and thin specimen.
* Light beam passes through convex objective lens.
* Image magnified and viewed through ocular lens.
59
what is the magnification of images produced by a compound light microscope?
Produce images with magnification up to 15003 depending on lenses.
60
What is important when observing microscopic detail? What is the maximum resolution for a compound light microscope?
- Importance of resolution in microscopy for observing structure detail.
* Maximum resolution for a compound light microscope is 200 nm (nanometres).
(* Best microscopes distinguish two separate structures if distance between objects is 200 nm or more.
* Viewing both living and non-living specimens is possible with a compound light microscope.)
61
What are the 3 type of mechanical adjustments in the light microscope? what are the 3 types of lens?
Adjustments:
- coarse adjustment
- Fine adjustment
- Condenser adjustment
Lens:
- Ocular Lens
- Objective Lens
- Condenser Lens
62
What is the difference between a fluorescence microscope and a light microscope?
Light microscopes use light in the 400-700nm range – the range through which light is visible to the human eye – but fluorescence microscopy uses much higher intensity light. Because traditional light microscopy uses visible light, the resolution is more limited.
63
How is a fluorescence microscope used?
* A sample is labeled with fluorescent substance for specific observation.
* Illuminates sample with high-intensity light, causing fluorescent substance to emit light.
* Fluorescent light is directed through filters, allowing viewing of only fluorescing areas.
64
What is an electron microscope? When was it invented? How does it work
- Electron microscope is a microscope developed since the 1950s,which revolutionized microscopic organism studies.
* Uses electron beam and electromagnets for greater magnification and higher resolving power.
65
What are the 2 types of electron microscopes?
* Two main types of electron microscopes:
- Scanning Electron Microscope (SEM) and
- Transmission Electron Microscope (TEM).
66
What is the Function of TEM?
- * TEM produces a two-dimensional image, can magnify up to 1,000,000 times, and has a resolution of about 2 nm.
67
What is the Function of SEM?
* SEM bombards solid specimens with a beam of electrons, emitted secondary electrons from the 3D surface layers, but has poorer resolution than TEM
68
What is the difference between light microscopes and electron microscopes? Which allows it do identify what?
- Uses electron beam and electromagnets for greater magnification and higher resolving power.
- Electron microscopes also have a much higher resolving power than light microscopes because electrons have a much shorter wavelength than light.
* Identifies structures at both cellular and subcellular levels.
* It demonstrated the structure of materials that was previously thought-to-be-less or no structure have been shown to have elaborate internal organisation.
69
How did electron microscope contribute to microscopic science?
* Electron microscopes have revolutionized the study of cells, enabling greater detail in organelles and understanding of their internal structure.
* Features as small as one-tenth of a nanometre, including individual atoms, can be observed.
70
What is an artifact in microscopy?
An artefact is something that is introduced into the image that wouldn’t normally be there. Comparing samples prepared in different ways can identify whether artefacts are present.
71
What are the disadvantages of using electron microscope?
* Vacuum placement required for viewing due to air interference.
* Complex specimen preparation risk of introducing artefacts.
* Larger size, expense, and maintenance costs compared to other microscopes.
* Comparing samples prepared differently can identify artefact presence.
72
How has digital processing helped scientist study cells?( Software/ Tech/ Scanning/Program)
(* Digital processing of microscope images allows scientists to view cells in new ways.)
* Cell scan software produces three-dimensional representations of cell structure, enhancing understanding of cell structure and function.
* Advanced computer technologies construct models to determine molecule interaction in cellular reactions.
* Confocal laser scanning microscopy highlights the three-dimensional structure of samples.[ Confocal laser scanning microscope takes an image of the sample at many different levels. A computer program is then used to construct a three-dimensional image.]
* An image reconstruction program combines data from different levels to construct a three-dimensional image.
* Microscopes are often used to image structural components of cells, preserving the specimen's integrity.
73
Summary of cell technologies?
Early Microscopes and Their Impact
* Early microscopes enabled scientists to see cells for the first time.
* Magnification and resolution indicate the size and distance of objects.
* Light microscopes pass light rays through thin specimens magnified by convex glass lenses.
* Light microscopes can view living and non-living specimens.
* Fluorescence microscopy targets specific structures using fluorescent substances.
* Electron microscopes use electron beams and electromagnets.
* Transmission electron microscopes (TEM) produce two-dimensional images, while scanning electron microscopes (SEM) create three-dimensional images.
* Confocal laser scanning microscopes combine multiple layers into a three-dimensional model.
74
What are the factors that determine the organelle arrangement in a cell?
Organelle Arrangement in Plant and Animal Cells
* Organelles arrangement varies based on cell type.
* Animal cells contain many organelles, while plant cells have cell wall, chloroplasts, and large vacuole.
* Plant cells have specific organelles, while animal cells lack them.
75
What do the arrangement of organelles depend on?
The arrangement of organelles also varies depending on whether the cell is a plant or animal cell
76
What are the 3 alternate names for cell membrane?
- plasma membrane,
- cytoplasmic membrane - plasmalemma
77
What are the 4 synonyms for cell membrane and function? What is its main feature? What is protoplasm? What is a cytoplasm? What is stored in cytoplasm(% of water)?
Cell Membranes and Protoplasm Overview
* Cell membrane, also known as plasma membrane, cytoplasmic membrane, or plasmalemma, surrounds cell contents and controls the passage of water and chemical substances.
* It is selectively permeable, allowing only certain molecules to pass into or out of cells.
* Both plant and animal cells have a cell membrane.
* Protoplasm, the living content of a cell responsible for respiration, consists of the nucleus and the cytoplasm.
* The cytoplasm contains a liquid called the cytosol, suspended organelles, and insoluble granules.
* Approximately 90% of the cytoplasm is water, the medium in which all cell chemicals are stored.
78
[ Prokaryotic cell structure]
What is a cell membrane? Temporary vacuole? Cytoplasm? Nuclear? Golgi apparatus? Endoplasmic reticulum? Mitochondrion? Ribosomes? Nucleus?
Cellular Structure Overview: Prokaryotic
* Cell membrane: outer barrier allowing substances to pass.
* Temporary vacuole: temporary storage sac.
* Cytoplasm: Fluid material for cell activities.
* Nuclear: Involved in ribosome manufacturing.
* Golgi apparatus: System of membranes for substance storage.
* Endoplasmic reticulum: Intracellular and intercellular transport system.
* Mitochondrion: Site of cellular respiration.
* Ribosomes: Sites of protein synthesis.
* Nucleus: Coordinates cell activities.
79
[ Eukaryotic cell structure ]
What is cell membrane? What is Nucleolus? Nucleus? Large permanent vacuole?
Cellular Structure Overview ( Eukaryotic cell)
* Cell membrane selectively allows certain substances to pass through.
* Nucleolus manufactures ribosomes within the cell.
* Nucleus coordinates all cell activities.
* Large permanent vacuole stores various materials.
* Chloroplast is photosynthesis site.
* Cytoplasm is fluid material where cell activities occur.
* Cell wall provides extra support and protection.
* Mitochondrion is site of cellular respiration.
* Nucleus is the control and information center.
* Surrounded by a double nuclear membrane, regulated by tiny pores for communication.
80
What are the organelles that eukaryotic cells and prokaryotic have in common?
- Cell membrane
- Cytoplasm
- Cytoskeleton
- Nucleus
- Mitochondria
- Endoplasmic reticulum
- Ribosomes
- Golgi body
81
What are the organelles that are specific to eukaryotic cells only? prokaryotic cells only?
1/
- Cell wall
- Chloroplasts
- Large, permanent vacuole
2/
- Lysosomes
- Centrioles
82
What are the synoyms for nucleus?(2)
What does it contain?(3)
What is DNA? What does DNA contain?
How is DNA passed down from one cell to another?
What does Chromatin separate into?
How is number of chromosomes determine?
Understanding the Structure and Function of the Nucleus
* The nucleoplasm, or nuclear sap, contains chromatin, a protein and nucleic acid.
* DNA, a large chemical, stores all genetic information necessary for cell function.
* DNA contains hereditary information passed from one generation to the next.
* Before cell division, DNA information must be copied for transmission.
* Chromatin separates into chromosomes, visible in dividing cells.
* Each species has a specific number of chromosomes, e.g., humans have 46, platypus has 52, lettuce has 18, camel has 70.
83
What is Nucleolus? What does it contain? its function?
Understanding Cellular Structure and Functions
Nucleolus and Ribosomes
* Nucleolus, a dense, granular region within the nucleoplasm, contains a large amount of nucleic acid, mostly RNA.
* Responsible for manufacturing organelles called ribosomes, the essential'machinery' of the cell.
84
What is endoplasmic reticulum? What type of ER does ribosomes attach themselves into? what is its function?
Endoplasmic Reticulum (ER)
* The outer nuclear membrane connects the nucleus and the cell's environment, facilitating intracellular transport.
* ER may have ribosomes attached (rough ER) or no ribosomes (smooth ER).
* Mainly transports, processes cell products, and transports substances from one cell to another.
85
What are ribosomes? What is created in ribosomes?
Ribosomes
* Small organelles made of RNA and protein, carry out genetically coded instructions of DNA to produce necessary proteins.
* Amino acids are joined to form polypeptides, the structural unit of proteins.
* Newly synthesised proteins pass from the ribosomes into the ER.
86
What is Golgi Body made and how does it differ from ER? Describe how it appears? How are the membranes arranged? What is its function?
Golgi Body Overview
Golgi Body
1/ * Made of flat membranes, differs from ER in not having ribosomes attached.
2/ * Recognizable by its curved shape on one surface, where vesicles can be seen.
* Recognized by a curved shape on one surface, where vesicles budding off.
3/* Membranes are arranged in stacks of four to 10.
4/ * Processes, packages, and sorts cell products.
* Adds proteins and carbohydrates to cell products.
* Provides a membrane around cell products for packaging.
* Membranes serve as a packaging label.
* Features of the membrane determine product destination, either internal transport or secretion.
87
What does the cell membrane of cell products made by the Golgi Body act as?
* Membranes serve as a packaging label.
* Features of the membrane determine product destination, either internal transport or secretion
88
Where are Lysosomes found in? what is its function? How does that happen? What is apoptosis? What happens when a lysosome membrane ruptures?
Cellular Organelles and Their Functions
Lysosomes and Cellular Regeneration
1&2 / * Lysosomes, found in animal cells, recycle and reuse organelles.
3/* They contain digestive enzymes that break down complex compounds into simpler ones.
4/ * They can sometimes destroy the entire cell through apoptosis or programmed cell death.
5/ * The lysosome membrane ruptures, releasing enzymes that digest the cell's contents, killing it.
89
What is mitochondria? How is the amount of mitochondria determined in each cell? What is the function of the mitochondria?
Mitochondria and Cellular Respiration
1/ * Mitochondria are the 'powerhouses' of a cell, producing energy through cellular respiration.
2/ * The number of mitochondria depends on the energy the cell needs to function.
3/ * Mitochondria combine oxygen with sugars during cellular respiration to release energy in a form that the cell can use.
90
Describe the structure of the mitochondrion? What is in the central space in a mitochondrion is filled with fluid?
* Each mitochondrion has a double membrane, the outer for shape and the inner for attachment of enzymes.
* The central space in a mitochondrion is filled with fluid, termed the matrix, containing mitochondrial DNA and enzymes.
91
What are vacuoles? What do they contain?
Vacuoles and Cellular Support
* Vacuoles are large, permanent, fluid-filled sacs in the cytoplasm of mature plant cells.
* They contain cell sap, a watery solution, and a single membrane, the tonoplast.
* Vacuoles provide support to plant cells by pushing outwards with the cytoplasm, exerting pressure on the cell wall, and keeping it firm.
92
What are chloroplasts? How large are they and what do they contain? Explain why do chloroplasts have a double membrane?
Understanding Plant Cell Structures
Chloroplasts and Photosynthesis
1/ * Chloroplasts are green organelles responsible for photosynthesis, the manufacturing of sugar in plants using sunlight.
2/ * They are found in green tissue of plants that can photosynthesise and are larger than mitochondria but also contain their own DNA.
3/ * Chloroplasts have a double membrane that allows substances to pass between the cytoplasm and the chloroplast.
* The layering of membranes increases the surface area over which chlorophyll occurs, allowing a large amount of sunlight to be absorbed for photosynthesis.
93
What is present in the stoma?
* All the enzymes needed for photosynthesis are present in the stoma, and simple sugars made during photosynthesis are stored in the stroma as starch grains.
94
What is the difference between call wall and cell membrane?
Plant Cell Wall and Centriosomes
* The cellulose cell wall that surrounds plant cells differs from the cell membrane inside it.
* Its structure allows it to provide strength and support, with strands of cellulose fibres having a little elasticity and being somewhat flexible.
* Some cell walls are thickened with additional chemicals that make the walls hard and woody (for example, in tree trunks) or that provide waterproofing (for example, in cork or the waxy cuticle of leaves).
95
What is a centrosome? What is a cytoskeleton?
Centrioles and Cytoskeleton
1/* The centrosome is a dense, granular structure that plays an important role in cell division, forming the spindle, which holds chromosomes in a dividing cell.
2/* The cytoskeleton keeps organelles in place, organizing their distribution and holding them in place by a network of tiny microtubules, microfilaments, and intermediate filaments.
96
What are organelles? what do most organelles have? How to organelles vary in size?
Organelles and Cell Structures
* Organelles are membrane-bound internal structures with specific functions to ensure the efficient functioning of the cell.
* Most organelles have structures that maximise the surface area.
* Organelles and other cell structures vary in size, with only the cell membrane, cell wall, nucleus, chloroplasts, and vacuoles being big enough to be observed using a light microscope
97
Who and when was the fluid mosaic model of cell membranes proposed? What is the function of the cell membrane? How does the model describe the cell membrane? what are embedded in the lipids and what to they help the cell membrane to do? What is the fluid part of the cell membrane composed of? What is there in animal cells that makes them more flexible? How is membrane flexibility increased in plants?
Understanding Cell Membrane Structure
* The fluid mosaic model of cell membranes, proposed by Singer and Nicolson in 1972, is the current accepted understanding of cell membrane structure.
* The model accounts for most functions associated with cell membranes and is compatible with various research methods.
* The cell membrane controls the exchange of material between the internal and external environments of the cell.
* The model describes the cell membrane as a double layer of lipids, a lipid bilayer, with the ability to flow and change shape.
* Specialized protein molecules are embedded in the lipid in various patterns, helping to control material exchange between the external and internal environments.
* The 'fluid' part of the cell membrane is composed of two layers of phospholipids forming a phospholipid bilayer.
(* The 'fluid' mosaic is not rigid in structure, hence the term 'fluid' mosaic.)
* In animal cells, cholesterol is interspersed among the phospholipid molecules, making the membrane more flexible.
* In plants, membrane flexibility is increased by phytosterol.
98
What are the parts an function of each phospholipid molecule?
*A phospholipid molecule. The hydrophilic head is attracted to water whereas the hydrophobic tails repel water.
99
What are the 2 properties of cell membranes ?what is the reason for it? What is interspersed throughout the lipid bilayer it cause and what does it form?
Cellular Membrane Structure and Proteins
1/ * Cell membranes are flexible and repairable, allowing cells to change shape and grow.
* Cell membranes can break and reassemble during processes like cell division.
2/ * Proteins are interspersed throughout the lipid bilayer, forming a mosaic effect.
* Some proteins penetrate the bilayer, forming channels for materials to cross.
100
What is embedded in the lipid bilayer? What is the function of the membrane's external surface? how are the membrane's external and intracellular environments regulated with?
1/ * Other proteins are partially embedded, 'floating' in the lipid bilayer.
* The membrane's external surface includes transport, receptor, recognition, and adhesion proteins.
* The membrane's external and intracellular environments are characterized by hydrophilic head, hydrophobic fatty-acid chains, cholesterol protein, and phospholipid bilayer.
101
What is the function of proteins in cells? What is function of glycoproteins? What is function of Adhesion proteins? Transport proteins? receptor proteins?
Cellular Protein Structure and Function
1/* Proteins in cells function as pores, active carrier systems, or transport channels.
2/
* Glycoproteins have carbohydrates attached for cell recognition.
* These proteins enable cell-to-cell interaction and communication.
3/
* Adhesion proteins in multicellular organisms maintain the organism's three-dimensional structure.
4/
* Transport proteins allow specific substances to move across the membrane.
5/
* Receptor proteins in cells respond to specific signals from substances like hormones.
102
What type of proteins(2) identify the cell and distinguish between foreign particles and the body's own cells? What is this feature called? What are the 3 types of proteins in the membrane? What does cholesterol or phytosterol provide the membrane with? What are models used for?
1/
* Membrane recognition proteins or glycoproteins identify the cell and distinguish between foreign particles and the body's own cells.
2/
* The cell membrane is selectively permeable and controls the movement of substances into and out of the cell.
(* The fluid mosaic model is the current accepted model of the cell membrane structure.)
3/
* Some membrane proteins form pores, some form active carrier systems, and others have carbohydrates attached for cell recognition.
4/
* Cholesterol or phytosterols provide some flexibility to the membrane.
5/
* Models are used in science to simplify concepts, make visual representations, or make predictions.
* Models need validation, relevance to actual parts, and documentation of model limitations.
103
What do further studies focus on? What do cell need? What does the cell memebrane control?
Cellular Structure and Function Study
* Development of technologies to view cell internal structure enables scientists to identify different cell types and structures.
* This knowledge fuels curiosity about cell function.
* Further studies focus on biochemical processes like photosynthesis and cellular respiration.
* Cells need external materials and internal waste removal for these processes.
* The nucleus coordinates these biochemical activities for efficient cellular metabolism.
* The cell membrane controls movement of cellular requirements and removal of cellular products and wastes.
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