Cell theory, components, structures, and function of cells Flashcards
(115 cards)
1
Q
What is the first key generalization of the cell theory?
A
All organisms are composed of one or more cells.
2
Q
What is the second key generalization of the cell theory?
A
The cell is the basic structural and functional unit of all living organisms.
3
Q
What is the third key generalization of the cell theory?
A
Cells arise only from the division of pre-existing cells.
4
Q
Why are the principles of cell theory foundational to biological science?
A
They established the understanding that all living organisms are made of cells, cells are the basic unit of life, and new cells come from existing cells.
5
Q
What do cells contain that carries hereditary information and directs the manufacture of cellular molecules?
A
DNA and RNA.
6
Q
How do cells use energy sources?
A
Cells use chemical molecules or light as energy sources to carry out essential life processes.
7
Q
What do cells do in response to changes in their external environment?
A
Cells alter their internal reactions to respond to changes in their external environment.
8
Q
What happens to cells during reproduction?
A
They duplicate and pass on hereditary information.
9
Q
Can most cells be seen with the naked eye?
A
No, most cells are invisible to the naked eye.
10
Q
What types of organisms are typically unicellular?
A
Most bacteria, archaea, some protists (like amoebas), and some fungi (like yeasts).
11
Q
How do multicellular organisms divide their life activities?
A
Life activities are divided among specialized cells.
12
Q
Can individual cells from multicellular organisms survive independently?
A
Yes, in a suitable chemical medium, individual cells can potentially survive independently.
13
Q
What happens if cells are broken open?
A
They lose the ability to grow, reproduce, or respond to stimuli in a coordinated manner.
14
Q
What confirms that life does not exist in units simpler than individual cells?
A
The inability of broken-open cells to grow, reproduce, or respond to stimuli in a coordinated manner.
15
Q
What does this chapter introduce that enhances our understanding of cell structure?
A
Modern microscopes.
16
Q
What are the typical sizes of prokaryotic cells compared to human cells?
A
Prokaryotic cells are typically a few micrometres in length and less than a micrometre in diameter, whereas a typical human cell has about ten times the diameter and over 8000 times the volume of an average prokaryotic cell.
17
Q
What are the common shapes of prokaryotic cells?
A
Spherical, rodlike, and spiral.
18
Q
Where is the genetic material located in prokaryotic cells?
A
In a nucleoid, a highly folded mass of DNA not separated by a membrane.
19
Q
What form does the DNA take in most prokaryotic species?
A
A single circular molecule forming the prokaryotic chromosom
20
Q
How is genetic information used in prokaryotic cells to make proteins?
A
DNA is transcribed into messenger RNA (mRNA), which ribosomes use to assemble amino acids into proteins.
21
Q
What are prokaryotic ribosomes composed of?
A
A large and a small subunit, each made of ribosomal RNA (rRNA) and proteins.
22
Q
What surrounds the plasma membrane of prokaryotic cells, providing structural support and protection?
A
A rigid cell wall.
23
Q
What is the glycocalyx, and what are its functions?
A
An external polysaccharide coating that helps protect cells from damage and desiccation and aids in attachment to surfaces.
24
Q
What vital functions does the plasma membrane perform in prokaryotic cells?
A
Transporting materials and metabolizing food molecules into ATP.
25
How do photosynthetic bacteria utilize light energy?
Molecules that absorb light energy are associated with the plasma membrane or internal membranes derived from it.
26
What internal structures do some photosynthetic bacteria have for photosynthesis?
Layers of internal membranes where photosynthesis occurs.
27
What cytoskeletal structures are found in prokaryotic cells, and what are their functions?
Filamentous structures that help maintain cell shape, facilitate cell division, and determine cell polarity.
28
How do many prokaryotes move?
Using flagella, long threadlike protein fibers that rotate to propel the cell.
29
What are pili, and what are their functions?
Hairlike protein structures that help attach the cell to surfaces or other cells. A special type, the sex pilus, facilitates the transfer of genetic material between bacteria during mating.
30
Into what four major groups is the domain Eukarya divided?
Protists, fungi, animals, and plants.
31
What characterizes eukaryotic cells?
Having a true nucleus enclosed by membranes and cytoplasmic organelles enclosed within a plasma membrane.
32
What are some functions of the membranous organelles in eukaryotic cells?
Energy metabolism, molecular synthesis, storage, and transport
33
What is the cytosol, and what are its functions?
The solution surrounding the organelles, participating in energy metabolism, molecular synthesis, and functions related to support and motility.
34
What are some functions of the eukaryotic plasma membrane?
Transporting substances into and out of the cell, binding signal molecules, and triggering internal responses
35
How do certain plasma membrane proteins in animal cells function in cell recognition?
They recognize and adhere to molecules on the surfaces of other cells and act as immune system markers identifying cells as "self."
36
What is the purpose of the supportive cell wall in fungal, plant, and many protist cells?
To provide structural support and protection.
37
Do animal cells have cell walls?
No, but they produce extracellular material with supportive and other functions.
38
What are the four major groups into which the domain Eukarya is divided?
Protists, fungi, animals, and plants.
39
What characterizes eukaryotic cells?
A true nucleus enclosed by membranes and cytoplasmic organelles enclosed within a plasma membrane.
40
What functions do the eukaryotic plasma membrane proteins facilitate?
Transporting substances into and out of the cell, binding signal molecules, and triggering internal responses.
41
What is the role of the supportive cell wall in fungal, plant, and many protist cells?
Providing structural support and protection.
42
How does the nucleus of eukaryotic cells differ from the nucleoid of prokaryotic cells?
The nucleus is separated from the cytoplasm by the nuclear envelope, containing much more DNA than the prokaryotic nucleoid.
43
What are lamins?
A network of protein filaments reinforcing the inner surface of the nuclear envelope in animal cells.
44
What is the function of nuclear pore complexes?
Regulating the exchange of materials between the nucleus and the cytoplasm.
45
What are chromatin and chromosomes?
Chromatin is a combination of DNA and proteins, while a chromosome is a single DNA molecule with its proteins.
46
What are nucleoli and their function?
Irregular masses of fibers and granules within the nucleus where rRNA genes are transcribed and ribosomal subunits are formed.
47
What are the two forms of eukaryotic ribosomes?
Free ribosomes suspended in the cytosol and membrane-bound ribosomes attached to the ER.
48
What is the endomembrane system?
A collection of interrelated internal membranous sacs that divide the cell into functional and structural compartments
49
What are the two forms of endoplasmic reticulum (ER) and their functions?
Rough ER (involved in protein synthesis and modification) and smooth ER (involved in lipid synthesis and detoxification).
50
What is the Golgi complex, and what is its role?
A stack of flattened membranous sacs that modify, sort, and package proteins and lipids for transport.
51
What are lysosomes and their function?
Small, membrane-bound vesicles containing hydrolytic enzymes that digest complex molecules, organelles, and cellular debris
52
How are lysosomes formed?
By budding from the Golgi complex.
53
What are mitochondria, and what is their primary function?
Mitochondria are membrane-bound organelles where cellular respiration occurs, breaking down energy-rich molecules to produce ATP.
54
What process occurs in mitochondria, and what are its products?
Cellular respiration occurs in mitochondria, resulting in the production of water, carbon dioxide, and ATP.
55
Why is oxygen essential for mitochondrial reactions?
Oxygen is required for the breakdown of fuels in cellular respiration to produce ATP.
56
Describe the structure of mitochondria.
Mitochondria have a smooth outer membrane and a highly folded inner membrane with infoldings called cristae that increase surface area for chemical reactions.
57
What is the significance of cristae in mitochondria?
Cristae increase the surface area of the inner membrane, providing more space for the chemical reactions involved in cellular respiration.
58
Do mitochondria contain their own genetic material?
Yes, mitochondria have their own DNA and ribosomes.
59
What is the evolutionary origin of mitochondria?
Mitochondria are believed to have evolved from ancient bacteria that became permanent residents of the cytoplasm during the evolution of eukaryotic cells.
60
What is the cytoskeleton?
The cytoskeleton is an interconnected system of protein fibers and tubes throughout the cytoplasm that maintains cell shape, internal organization, and movement.
61
Which cells have a highly developed cytoskeleton?
Animal cells have a highly developed cytoskeleton.
62
What are the three major types of structural elements in the cytoskeleton?
The three major types of structural elements in the cytoskeleton are microtubules, intermediate filaments, and microfilaments.
63
What are microtubules made of and what is their role?
Microtubules are made of tubulin dimers and they anchor various organelles, provide tracks for vesicle movement, and play roles in cell division, chromosome movement, and maintaining cell shape.
64
What do motor proteins like dyneins and kinesins do?
Dyneins and kinesins are motor proteins that facilitate movement along microtubules, powered by ATP.
65
What are intermediate filaments and their function?
Intermediate filaments have diameters between microtubules and microfilaments and provide structural support in cells and tissues, holding the nucleus in place in epithelial cells.
66
What are microfilaments made of and what processes do they assist with?
Microfilaments are composed of actin subunits and are involved in cytoplasmic streaming, cell division, and muscle contraction
67
What is the role of the motor protein myosin?
Myosin facilitates movement along microfilaments during processes like cytoplasmic streaming and muscle contraction.
68
What is the arrangement of microtubules in flagella and cilia?
Flagella and cilia have a 9 + 2 arrangement of microtubules.
69
Where do flagella and cilia originate from?
Flagella and cilia originate from centrioles, which migrate to positions just beneath the plasma membrane, forming the basal body of these structures.
70
What is the difference between flagella and cilia?
Flagella are typically longer and fewer in number, while cilia are shorter and more numerous.
71
What are some examples of cells with flagella?
Examples include sperm cells and reproductive cells of some plants.
72
Where can cilia be found and what are their functions?
Cilia can be found on cell surfaces lining cavities or tubes in the body, like in brain ventricles for fluid circulation and in the oviducts for egg transport.
73
Do eukaryotic flagella and prokaryotic flagella share the same evolutionary origin?
No, the genes encoding their components differ, indicating independent evolutionary origins.
74
Are lysosomes present in all eukaryotic cells?
No, lysosomes are restricted to animal cells.
75
What are the specialized structures found in plant cells?
Plant cells have chloroplasts, central vacuoles, and cell walls.
76
What is the primary function of chloroplasts in plant cells?
Chloroplasts are the sites of photosynthesis.
77
What family of organelles do chloroplasts belong to?
Chloroplasts belong to a family of organelles known as plastids.
78
What do amyloplasts and chromoplasts do?
Amyloplasts store starch, while chromoplasts contain pigments responsible for fruit and leaf colors
79
Describe the structure of chloroplasts.
Chloroplasts are lens or disc-shaped, with smooth outer and inner membranes, enclosing the stroma and thylakoids stacked to form grana.
80
What do thylakoid membranes contain?
Thylakoid membranes contain light-absorbing molecules like chlorophyll.
81
What is the role of enzymes in the stroma of chloroplasts?
Enzymes in the stroma produce carbohydrates and other organic molecules using energy from photosynthesis.
82
How do chloroplasts suggest an ancient bacterial origin?
Chloroplasts have DNA and ribosomes similar to those found in certain photosynthetic bacteria.
83
What are central vacuoles and their role in plant cells?
Central vacuoles are large vesicles that store substances, provide structural support, and help cell growth.
84
What percentage of a mature plant cell's volume can be occupied by central vacuoles?
Up to 90% of the cell's volume can be occupied by central vacuoles.
85
What is the tonoplast membrane?
The tonoplast membrane surrounds central vacuoles and contains transport proteins.
86
What functions do central vacuoles serve?
They store salts, organic acids, sugars, proteins, pigments, waste products, and contain enzymes for digestion.
87
What are cell walls composed of?
Cell walls are composed of cellulose fibers embedded in a network of highly branched carbohydrates.
88
What are plasmodesmata?
Plasmodesmata are cytosol-filled channels in cell walls that allow ions and small molecules to move between plant cells.
89
How do cell walls in fungi differ from those in plant cells?
Some fungi incorporate chitin into their cell walls instead of cellulose.
90
Do animal cells have cell walls?
No, animal cells lack rigid cell walls but have extracellular material and surface structures for support.
91
What are Cell Adhesion Molecules (CAMs)?
CAMs are integral glycoproteins in the plasma membrane that maintain tissue and organ structural integrity by selectively binding to specific molecules on neighboring cells.
92
What role do CAMs play during embryonic development?
CAMs facilitate initial cell connections that undergo dynamic rearrangements as cells and tissues change positions, eventually becoming permanent and reinforced by more complex cell junctions
93
What happens when CAM function is disrupted in cancer cells?
Cancer cells often lose their adhesion properties, enabling them to detach, migrate, and form secondary tumors.
94
How do CAMs contribute to the immune system?
CAMs help the immune system distinguish between self and non-self, playing a role in organ transplant rejection by triggering an immune response to foreign cell surface molecules.
95
What are the three main types of cell junctions in animal cells?
The three main types are anchoring junctions, tight junctions, and gap junctions.
96
What is the function of anchoring junctions?
Anchoring junctions "weld" adjacent cells together, providing stability in tissues subjected to mechanical forces like stretching or shearing.
97
What do tight junctions do?
Tight junctions create tight connections between adjacent cell membranes, sealing the intercellular space and preventing leakage of particles.
98
How do gap junctions facilitate cell communication?
Gap junctions provide direct channels between the cytoplasm of adjacent cells, allowing ions and small molecules to pass freely for rapid communication.
99
What is the Extracellular Matrix (ECM)?
The ECM is a network of proteins and polysaccharides secreted by cells, providing protection, structural support, and influencing cellular processes.
100
What are the primary components of the ECM?
The primary components are glycoproteins like collagen, which provides tensile strength and elasticity, and proteoglycans, which form a network around collagen fibers.
101
What is the role of fibronectins in the ECM?
Fibronectins help organize the ECM and attach cells to it by binding to integrin receptor proteins, which link to the cell's cytoskeleton
102
How does the ECM influence tissue development and responses to injuries?
The ECM supports tissue architecture, sustains cellular functions, and modulates responses to physiological cues and pathological insults.
103
Into which three domains are all forms of life classified?
Bacteria, Archaea, and Eukarya.
104
Why are bacteria and archaea no longer grouped together as Prokaryota?
Recent research has shown they are not evolutionarily related.
105
What are the two common types of microscopes used to view cells?
Light microscopes and electron microscopes.
106
Why do electron microscopes provide higher resolution than light microscopes?
Because electrons have a shorter wavelength compared to light
107
How does the surface area-to-volume ratio affect cell function?
As cell diameter increases, the volume grows faster than the surface area, affecting the cell’s ability to exchange nutrients and waste.
108
What adaptations do some cells have to enhance nutrient and waste exchange?
Surface folds or extensions, such as fingerlike extensions in human intestinal cells.
109
What is the plasma membrane, and what is its function?
A bilayer of lipids with embedded proteins that acts as a hydrophobic barrier to water-soluble substances, allowing selective passage through transport proteins.
110
What is contained in the central region of all cells?
DNA, which stores hereditary information, proteins that maintain DNA structure, and enzymes for DNA replication and RNA transcription.
111
What is the cytoplasm, and what does it contain?
The area between the plasma membrane and the central region, containing organelles, cytosol, and the cytoskeleton.
112
What are the functions of the cytoskeleton in the cytoplasm?
It helps maintain cell shape and is crucial in cell division and chromosome segregation.
113
What are the two types of cells, and how are they different?
Prokaryotic (lacking a nucleus, with a nucleoid) and eukaryotic (having a membrane-bound nucleus).
114
What defines eukaryotic cells?
The presence of a membrane-bound nucleus containing the cell's DNA and extensive membrane systems forming organelles.
115
What is a key feature of prokaryotic cells?
They lack a nucleus, with a DNA-containing central region called the nucleoid not separated from the cytoplasm by a membrane.
