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Cell Flashcards

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1
Q

Cell

A

Acell is a chemical system that is able to maintain its structure and reproduce.

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2
Q

Cell Theory:

A

• Basic unit of life; all chemical reactions that makes us alive happens in the cell
• All cells arrives from existing cells
• Is a building block for all living organisms:
• Unicellular
• Multicellular:
• Each type of cell with a specific function
• Immune cells fight against pathogens
Cell theory is a unifying principle of biology and is based on experimentation and the invention of the microscope. It
was first formulated in the mid-nineteenth century by Theodor Schwann and Matthias Schleiden.

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3
Q

Cell theory is a unifying principle of biology and is based on experimentation and the invention of the microscope. It
was first formulated in the mid-nineteenth century by

A

Theodor Schwann and Matthias Schleiden.

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4
Q

Cell components:

A

• Membrane – boundary
• Cytoplasm – contains organelles
• Nucleus – contains DNA

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5
Q

Modern cell theory

A

Modern cell theory is a widely accepted explanation of the relationship between cells and living things. It has several main principles
including:
Cells are the basic unit: Cells are the fundamental structural and functional unit of all living things.
Cells come from other cells: New cells are created from existing cells through cellular division.
Cells contain DNA: Cells contain DNA, which is found in the chromosome, and RNA, which is found in the cell nucle
and cytoplasm.
Cells have similar chemical composition: Cells in organisms of similar species have a similar chemical composition.
Energy flow occurs within cells: Energy flow, or metabolism and biochemistry, takes place within cells.
Organism activity depends on cell activity: The activity of an organism is the result of the combined actions of
individual cells

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6
Q

Prokaryotic cells

A

Prokaryotes are single-celled organisms of the domains
Bacteria and Archaea.
• All prokaryotes have plasma membranes, cytoplasm,
ribosomes, and DNA that is not membrane-bound.
• Most have peptidoglycan cell walls, and many have
polysaccharide capsules. Prokaryotic cells range in
diameter from 0.1 to 5.0 μm.
• As a cell increases in size, its surface area-to-volume ratio
decreases. If the cell grows too large, the plasma membrane
will not have sufficient surface area to support the rate of
diffusion required for the increased volume
• few or no membrane enclosed spaces within the cytoplasm
• no nucleus - DNA is in a region called the nucleoid
• DNA is circular and naked (has no protein associated with
it)
EU

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7
Q

Dna in prokaryotic cells

A

• no nucleus - DNA is in a region called the nucleoid
• DNA is circular and naked (has no protein associated with
it)

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8
Q

Cel organellesx

A

plasma membrane is a phospholipid bilayer embedded with proteins. The
nucleus’s nucleolus is the site of ribosome assembly. We find ribosomes either in
the cytoplasm or attached to the cytoplasmic side of the plasma membrane or
endoplasmic reticulum that perform the protein synthesis.
• Mitochondria participate in cellular respiration. They are responsible for the
majority of A TP produced in the cell. Peroxisomes hydrolyze fatty acids, amino
acids, and some toxins. V esicles and vacuoles are storage and transport
compartments. In plant cells, vacuoles also help break down macromolecules.

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9
Q

Animal cells

A

Animal cells also have a centrosome and lysosomes. The centrosome has two
bodies perpendicular to each other, the centrioles, and has an unknown purpose in
cell division. Lysosomes are the digestive organelles of animal cells.

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10
Q

Plant cells

A

Plant cells and plant-like cells each have a cell wall, chloroplasts, and a central
vacuole. The plant cell wall, whose primary component is cellulose, protects the
cell, provides structural support, and gives the cell shape. Photosynthesis takes
place in chloroplasts. The central vacuole can expand without having to produce
more cytoplasm.

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11
Q

Plasma membrane

A

The plasma membrane is a phospholipid bilayer with embedded
proteins. There are other components, such as cholesterol and
carbohydrates, which can be found in the membrane in addition to
phospholipids and protein.

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12
Q

The biochemical
machinery for trapping
light energy is contained
within a highly folded

A

Plasma membrane

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13
Q

The biochemical
machinery for trapping
light energy is contained
within a highly folded

A

Plasma membrane

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14
Q

Nuclear membrane

A

– envelope
• Nuclear pores – allows passage in & out
• Surrounded by rough endoplasmic
reticulum

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15
Q

Nucleoplasm

A

– inside the nucleus
• Contains:
• the nucleolus – where rRNA is made
• DNA – under the form of chromatin

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16
Q

Nuclear envelope

A

The outermost boundary of the nucleus is the nuclear envelope.
Notice that the nuclear envelope consists of two phospholipid
bilayers (membranes)—an outer membrane and an inner
membrane—in contrast to the plasma membrane, which consists
of only one phospholipid bilayer.

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17
Q

Chromosomes

A

: Described as “colored bodies,” chromosomes consist of DNA and proteins. They appear in a highly condensed form during cell division.

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18
Q

DNA and Protein State:

A

• Outside of cell division, the DNA and proteins are in a threadlike state, referred to as chromatin.

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19
Q

Histones:

A

These are the most common proteins found in chromatin. DNA wraps around histones in a repeating pattern.

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20
Q

Histones:

A

These are the most common proteins found in chromatin. DNA wraps around histones in a repeating pattern.

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21
Q

Nucleosomes

A

: These are the structural units formed when DNA is coiled around histone proteins.

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22
Q

T/F Chromosomes are only visible during cell division. ()

A

Answer: True

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23
Q

T/F The threadlike form of DNA and proteins during non-division phases is called chromatin. (

A

Answer: True

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24
Q

T/F Nucleosomes are made up of RNA and histone proteins. ()

A

Answer: False

DNA
CENTRAL HISTONE
SPACER HISTONE

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25
During cell division, DNA and proteins condense to form structures called _______. ()
Answer: Chromosomes
26
The DNA-protein complex in its threadlike state is called _______.
Chromatin
27
_______ are the proteins around which DNA coils in a regular pattern.
Histones
28
What is the main function of histone proteins?
Helping DNA coil into nucleosomes
29
What is the structural unit of DNA packaging in eukaryotic cells?
Nucleosomes
30
What is the appearance of DNA during interphase?
Chromatin (threadlike)
31
Why is the DNA condensed into chromosomes during cell division?
To ensure the DNA is evenly and accurately distributed into the daughter cells.
32
Explain the role of nucleosomes in DNA organization.
Nucleosomes compact the DNA by coiling it around histone proteins, allowing it to fit within the nucleus and regulate gene expression.
33
What is the difference between chromatin and chromosomes?
Chromatin is the uncondensed, threadlike form of DNA and proteins during the non-dividing phases, while chromosomes are the condensed form during cell division.
34
Chromosome
• “Chromosome” means “colored body.” • Composed of both DNA and proteins. • Highly condensed and visible during cell division. • In non-dividing cells, the DNA and protein exist in a thread-like form called chromatin.
35
Structure of Chromosomes:
• DNA is wrapped around histone proteins. • Forms repeating units called nucleosomes. • Central histones and spacer histones contribute to the structure. • This coiling allows DNA to compact and fit within the nucleus.
36
Role of Histones:
• Histones are the most common proteins in chromosomal structure. • They facilitate DNA organization by acting as spools around which DNA winds.
37
Function of Chromosomes:
• Carry genetic information. • Essential for cell division, growth, and reproduction.
38
What does the term “chromosome” mean?
Colored body
39
What is the thread-like form of DNA and protein called in non-dividing cells?
Chromatin
40
What are the most common proteins found in chromosomes?
Histones
41
What is the structural unit formed when DNA is coiled around histones?
Nucleosomes
42
Which part of the chromosome interacts with histones?
DNA
43
Why is DNA coiled around histones?
To compact it for fitting in the nucleus
44
What is the main purpose of chromosomes during cell division?
Distribute genetic material equally
45
Here is a list of membrane-bound organelles found in eukaryotic cells:
1. Nucleus • Structure: Double membrane with nuclear pores. • Function: Contains the cell’s genetic material (DNA) and regulates gene expression. 2. Mitochondria • Structure: Double membrane with inner folds called cristae. • Function: Produces ATP through cellular respiration (the “powerhouse of the cell”). 3. Endoplasmic Reticulum (ER) • Structure: Network of membranous tubules and sacs. • Rough ER: Studded with ribosomes. • Smooth ER: Lacks ribosomes. • Function: • Rough ER: Synthesizes and modifies proteins. • Smooth ER: Synthesizes lipids, detoxifies substances, and stores calcium ions. 4. Golgi Apparatus • Structure: Stacks of flattened membranous sacs. • Function: Modifies, sorts, and packages proteins and lipids for transport. 5. Lysosomes (in animal cells) • Structure: Membrane-bound vesicles containing digestive enzymes. • Function: Breaks down waste, pathogens, and damaged organelles (intracellular digestion). 6. Peroxisomes • Structure: Membrane-bound vesicles. • Function: Breaks down fatty acids, amino acids, and detoxifies harmful substances. 7. Vacuoles • Structure: Membrane-bound sacs, prominent in plant cells. • Function: • Stores water, nutrients, and waste. • Provides turgor pressure in plant cells. 8. Chloroplasts (in plant and algae cells) • Structure: Double membrane with internal structures called thylakoids. • Function: Conducts photosynthesis, converting solar energy into chemical energy (glucose). 9. Vesicles • Structure: Small membrane-bound sacs. • Function: Transport materials within the cell and to/from the cell membrane. 10. Endosomes • Structure: Membrane-bound compartments formed by endocytosis. • Function: Sorts and delivers internalized materials to lysosomes or back to the membrane. 11. Nuclear Envelope • Structure: Double membrane surrounding the nucleus. • Function: Protects the nucleus and regulates transport through nuclear pores. These organelles perform specific roles essential for cell survival and functionality. Let me know if you’d like a more detailed explanation of any!
46
Key Details About Chloroplasts Structure:
1. Two membranes: • Outer membrane: Protective boundary. • Inner membrane: Regulates the passage of materials.
47
Stroma
: • The fluid inside the chloroplast where the Calvin cycle occurs. • Contains enzymes, DNA, and ribosomes.
48
Thylakoids
: • Flattened sacs within the stroma. • Contain chlorophyll, the pigment responsible for capturing light energy. • Organized into stacks called grana (singular: granum).
49
Lumen:
• The space inside a thylakoid.
50
Additional Functions of chloroplast
• Starch synthesis and storage: In roots and tubers. • Pigment storage: Contributes to the ripened color of fruits.
51
Unique Features of chloroplast
• Have their own DNA, resembling prokaryotic DNA. • Can synthesize some of their proteins using prokaryotic-like ribosomes. • Divide independently through a process similar to prokaryotic cell division (binary fission).
52
Grana are stacks of thylakoids inside the chloroplast. (
Answer: True)
53
Chloroplasts have a single membrane. (
Answer: False) double
54
The fluid-filled region inside a chloroplast is called the _______.
Stroma
55
The green pigment in chloroplasts responsible for absorbing light is _______.
Chlorophyll
56
Chloroplasts replicate through a process similar to _______ cell division.
Prokaryotic
57
What is the function of thylakoids? • A) Transport proteins • B) Absorb light energy for photosynthesis • C) Store DNA • D) Synthesize lipids ()
Answer: B
58
Where does the Calvin cycle occur?
Stroma
59
Which characteristic makes chloroplasts similar to prokaryotes?
DNA and ribosomes
60
Why are chloroplasts considered semi-autonomous organelles?
They have their own DNA and ribosomes, allowing them to synthesize some of their own proteins and replicate independently.
61
Describe the relationship between the grana, thylakoids, and stroma.
Grana are stacks of thylakoids located in the stroma, where the thylakoids contain chlorophyll and other molecules required for the light-dependent reactions of photosynthesis.
62
What roles do chloroplast pigments play apart from photosynthesis? (
Answer: They can provide color to fruits, aiding in seed dispersal by attracting animals.)
63
Ribosomes
Structure: • Not membrane-bound: Unlike most organelles, ribosomes are composed of rRNA (ribosomal RNA) and proteins. • Two subunits: • Large subunit • Small subunit • Found: • Attached to the Rough Endoplasmic Reticulum (RER). • Freely floating in the cytoplasm. • Shape: Round or granular.
64
Function of ribosome
• Protein Synthesis: • Ribosomes are the site of translation, where mRNA is decoded to synthesize polypeptides (proteins). • They assemble amino acids into proteins based on the genetic instructions carried by mRNA.
65
Mitochondria Structure:
• Double membrane: • Outer membrane: Smooth and permeable to small molecules. • Inner membrane: Folded into structures called cristae to increase surface area for ATP production. • Intermembrane Space: The region between the inner and outer membranes. • Matrix: The innermost compartment, containing enzymes, DNA, and ribosomes.
66
Function of mitochondrial
• Known as the “powerhouse of the cell.” • ATP Production: • Site of aerobic respiration and energy generation via the electron transport chain and Krebs cycle. • Contains its own DNA (similar to prokaryotic DNA) and ribosomes, enabling mitochondria to synthesize some of their own proteins. • Reproduce by binary fission, similar to prokaryotic cell division.
67
T/F Ribosomes are membrane-bound organelles. (
Answer: False)
68
T/F Mitochondria have their own DNA and ribosomes. (
Answer: True)
69
T/F Ribosomes are involved in the synthesis of lipids. (
Answer: False)
70
The folding of the inner mitochondrial membrane forms _______ to increase the surface area for ATP production. (
Answer: Cristae)
71
The process of _______ occurs on ribosomes, where mRNA is translated into proteins.)
(Answer: Translation
72
The innermost compartment of the mitochondria, which contains enzymes and DNA, is called the _______. (
Answer: Matrix)
73
Where are ribosomes found in the cell?
Attached to the rough ER and freely in the cytoplasm
74
Which of the following functions is performed by mitochondria
ATP production Aerobic respiration Housing DNA and ribosomes
75
Ribosomes are made up of:
rRNA and proteins
76
Explain why mitochondria are considered semi-autonomous.
Mitochondria have their own DNA and ribosomes, allowing them to synthesize some proteins independently of the nucleus and to replicate via binary fission.
77
What is the primary difference between free ribosomes and ribosomes attached to the RER?
(Answer: Free ribosomes synthesize proteins that function in the cytoplasm, while ribosomes attached to the RER synthesize proteins destined for secretion or use in membranes.)
78
Why is the folding of the inner mitochondrial membrane important?
(Answer: The folds, called cristae, increase the surface area available for enzymes involved in the electron transport chain and ATP synthesis.)
79
Lysosomes
Structure: • Membrane-bound vesicles. • Contain digestive enzymes (e.g., hydrolases) that operate in a low pH environment. • Formed by the Golgi apparatus.
80
Function:of lysosomes
1. Intracellular Digestion: • Breaks down food particles, cellular debris, and engulfed pathogens. • Especially active in phagocytic cells like macrophages. 2. Garbage Disposal: • Removes broken or damaged organelles via a process called autophagy. 3. Contributes to immune defense by degrading pathogens.
81
The Endomembrane System Structure:
A network of membrane-bound organelles involved in the synthesis, modification, and transport of proteins and lipids. It includes: 1. Plasma Membrane: Regulates material exchange between the cell and its environment. 2. Nuclear Envelope: Surrounds the nucleus, allowing material exchange via nuclear pores. 3. Rough Endoplasmic Reticulum (RER): Synthesizes and modifies proteins. 4. Smooth Endoplasmic Reticulum (SER): Synthesizes lipids and detoxifies chemicals. 5. Golgi Apparatus: Modifies, packages, and sorts proteins and lipids. 6. Lysosomes: Degrade unwanted materials.
82
Function of endomembrane system
• Coordinates the production, modification, and transport of biomolecules like proteins and lipids. • Facilitates intracellular and extracellular communication.
83
T/F Lysosomes have a high pH to activate their enzymes.
(Answer: False; they operate at a low pH.) acidic
84
The Golgi apparatus is not part of the endomembrane system.
(Answer: False)
85
Lysosomes are only involved in digesting food particles.
(Answer: False; they also break down cellular debris and pathogens.)
86
Lysosomes maintain a _______ environment to activate their digestive enzymes.
Low pH
87
The endomembrane system includes the _______ and _______ ER.
Rough and smooth
88
_______ is the process where lysosomes break down damaged organelles.
Autophagy
89
Which organelle is primarily responsible for producing lysosomes?
Golgi apparatus
90
What is the role of the Rough Endoplasmic Reticulum (RER)?
Synthesize proteins
91
Which component is NOT part of the endomembrane system? • A) Lysosomes • B) Golgi Apparatus • C) Plasma Membrane • D) Mitochondria
Mitochondria
92
Extracellular Matrix (ECM) - Animals
• Composed of: • Collagen (protein for structural support). • Glycoproteins (proteins combined with sugars). • Function: • Provides protection against tension and compression. • Facilitates communication between cells through a network of substances secreted by cells.
93
Cell Wall - Plants
• Made of cellulose and other carbohydrates like pectin. • Function: • Provides rigidity, protection, and structural support. • Prevents excessive water uptake.
94
Plant-Specific Structures
1. Cell Plate: • Forms during cell division between two daughter cells. 2. Middle Lamella: • Adhesive layer rich in pectin, laid between the new cell walls of daughter cells. 3. Primary Wall: • Thin and flexible, allows cell growth. 4. Secondary Wall: • Forms after the primary wall, providing additional strength.
95
T/F. The extracellular matrix (ECM) is found in both plant and animal cells.
(Answer: False; it’s found in animal cells.)
96
T/F The cell wall of plant cells is primarily made of pectin. (
Answer: False; it’s primarily made of cellulose.)
97
The middle lamella is responsible for sticking adjacent plant cells together. (
Answer: True)
98
The plant cell wall is primarily composed of _______. (
Cellulose
99
The _______ in animal cells consists of proteins like collagen and glycoproteins.
Extracellular matrix
100
During cell division in plants, the _______ forms between two daughter cells.
Cell plate
101
The middle lamella in plant cells is rich in
Pectin
102
How do the ECM and the plant cell wall differ in composition and function?
Answer: The ECM in animals is composed of proteins (e.g., collagen) and glycoproteins, providing support and communication. The plant cell wall is made of cellulose and pectin, offering rigidity and protection.)
103
How do the ECM and the plant cell wall differ in composition and function?
Answer: The ECM in animals is composed of proteins (e.g., collagen) and glycoproteins, providing support and communication. The plant cell wall is made of cellulose and pectin, offering rigidity and protection.)
104
What is the purpose of the secondary cell wall in plants? (
Answer: The secondary cell wall provides additional strength and rigidity to mature plant cells.)
105
Describe the role of the cell plate during plant cell division. (
Answer: The cell plate forms between two daughter cells during cell division, eventually developing into a new cell wall.)
106
CYTOSKELETON
The cytoskeleton is a network of protein filaments and tubules that provides structural support and facilitates movement in the cell.
107
Microtubules
: • Made of tubulin proteins. • Functions: • Transport vesicles and organelles within the cell. • Form the mitotic spindle during cell division. • Enable cell movement via flagella and cilia.
108
Intermediate Filaments:
• Provide mechanical support and maintain cell shape. • Example: Keratin in epithelial cells.
109
Microfilaments
: • Made of actin proteins. • Functions: • Enable cell movement (e.g., pseudopodia). • Facilitate muscle contraction. • Form the cleavage furrow during cell division.
110
CENTRAL VACUOLE (PLANT CELLS)
The central vacuole is a large, membrane-bound organelle unique to plant cells, playing a critical role in storage and maintaining cell pressure. Features: • Filled with water and solutes (e.g., nutrients, ions). • Creates turgor pressure by drawing water into the vacuole due to a high solute concentration, causing the cell to expand. • Surrounded by the cell wall, which prevents bursting during expansion. Functions: 1. Stores nutrients, waste products, and water. 2. Maintains turgor pressure, providing structural support to the plant. 3. Helps in cell elongation during growth.
111
Cilia:
• Structure: • Many in number. • Short and hair-like. • Function: • Move substances across cell surfaces (e.g., mucus in the respiratory tract). • Aid in cell movement.
112
Flagella:
• Structure: • 1 or 2 per cell surface. • Long and whip-like. • Function: • Facilitate cell movement (e.g., sperm cells). • In prokaryotes, they rotate like a propeller, powered by a proton gradient.
113
Endosymbiosis and Evolution
• Definition: • A form of symbiosis where one organism lives inside another. • Endosymbiotic Theory: • Suggests mitochondria and chloroplasts originated as independent prokaryotic organisms that were engulfed by ancestral eukaryotic cells. • Evidence: 1. Both organelles have their own circular DNA. 2. Contain prokaryotic-like ribosomes. 3. Replicate independently via binary fission.
114
Prokaryotic vs. Eukaryotic Cells
Prokaryotic Cells (e.g., bacteria): • No membrane-bound organelles. • DNA is not enclosed in a nucleus. • Have structures like: • Capsule • Cell wall • Cytoplasmic membrane • Flagella • Pili Eukaryotic Cells (protists, fungi, plants, animals): • Contain membrane-bound organelles like: • Nucleus • Mitochondria • Golgi apparatus • ER • Lysosomes • More complex structure with a cytoskeleton and flagella.
115
T/F Endosymbiotic theory states that mitochondria and chloroplasts originated from prokaryotic organisms. ()
Answer: True
116
According to the endosymbiotic theory, mitochondria and chloroplasts were originally _______.
Prokaryotic organisms
117
Prokaryotic cells lack _______ but have ribosomes. (
Answer: membrane-bound organelles)
118
Which structure is primarily responsible for cell movement in prokaryotic cells?
Flagella
119
What type of ribosomes are found in mitochondria and chloroplasts?
Prokaryotic-like
120
Explain how the structure of flagella differs between prokaryotes and eukaryotes.
In prokaryotes, flagella have a rotary motor mechanism powered by a proton gradient. In eukaryotes, flagella are made of microtubules arranged in a 9+2 structure and move by whipping or undulating.
121
Why is the endosymbiotic theory significant in understanding the evolution of eukaryotic cells?
(Answer: It explains how complex eukaryotic cells acquired energy-producing organelles (mitochondria and chloroplasts), enabling the development of multicellular organisms.)
122
List two structural differences between prokaryotic and eukaryotic cells.
(Answer: Prokaryotic cells lack a nucleus and membrane-bound organelles, whereas eukaryotic cells have both. Prokaryotic cells also have a simpler cytoskeleton compared to eukaryotic cells.)

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