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General Bio 1 for science majors > Chapter 6 > Flashcards

Chapter 6 Flashcards

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1
Q

What is magnification?

A

The ratio of an object’s image size to its real size

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2
Q

What is resolution?

A

The measure of clarity of the image; or the minimum distance of two distinguishable points

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3
Q

What is contrast?

A

Visible differences in brightness between parts of the sample

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4
Q

What can light microscopes (LM) magnify to?

A

About 1,000x

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5
Q

What does a scanning electron microscope do?

A

Send a beam of electrons onto a specimen, and generates a 3-D image (ish)

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6
Q

What does a transmission electron microscope do?

A

Send a beam of electrons through a specimen

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7
Q

What is cell fractionation?

A

Takes cells apart and separates major organelles from each other

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8
Q

How do you fractionate cells?

A

With a centrifuge, different organelles drop to the bottom of a test tube with different speeds and gravitational speed

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9
Q

What domains consist of prokaryotic cells?

A

Archaea and Bacteria

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10
Q

What are the types of cells? (broad)

A

Prokaryotic and Eukaryotic

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11
Q

What are the basic features of all cells?

A

Plasma membranes
Semifluid substances (cytosol/cytoplasm) Chromosomes (DNA/genes)
Ribosomes (make proteins)

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12
Q

What are the defining characteristics of prokaryotes?

A

No nucleus, DNA in an unbound region called the nucleoid
No membrane bound organelles
Cytoplasm bound by plasma membrane

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13
Q

Eukaryotic defining characteristics?

A

DNA in a nucleus that is bound by a double membrane
Membrane bound organelles
Cytoplasm in the region between the plasma membrane and nucleus
Generally much larger than prokaryotes

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14
Q

What sets the size limit on cells?

A

Metabolic requirements; surface area to volume; volume grows more proportionally than surface area

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15
Q

What is a plasma membrane composed of?

A

A phospholipid bilayer; hydrophilic heads to the outside on each side and the hydrophobic tails inside

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16
Q

What is the nucleus?

A

Contains most of the DNA and genes in a eukaryotic cell
Ribosomes use information from DNA to make proteins

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17
Q

What are the parts of the nucleus?

A

Nuclear envelope
Nucleolus
Chromatin

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18
Q

What are nuclear lamina?

A

Structures on the nuclear side of the envelope that are composed of proteins that maintains the shape of the nucleus

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19
Q

What are nuclear pores?

A

They regulate entry/exit of molecules from the nucleus

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20
Q

What is the nuclear envelope?

A

Encloses the nucleus, separating nucleus from cytoplasm, and is a double membrane (two phospholipid bilayers)

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21
Q

What is DNA organized into?

A

Discrete units called chromosomes

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22
Q

What does chromatin do?

A

Condenses to form discrete chromosomes as a cell prepares to divide

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23
Q

What are chromosomes?

A

Each one contains one DNA molecule associated with proteins called chromatins

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24
Q

What is the site of ribosomal RNA synthesis?

A

The nucleolus (within nucleus)

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25
What are ribosomes?
Complexes made of ribosomal RNA and protein
26
Where are ribosomes located/build proteins?
In the cytosol (free ribosomes) On the outside of the endoplasmic reticulum or nuclear envelope (bound ribosomes)
27
What does the endomembrane system consist?
Nucelar envelope ER Golgi apparatus Lysosomes Vacuoles Plasma membranes
28
What is the endoplasmic reticulum?
It is continuous with the nuclear envelope Has two distinct regions: Smooth and Rough Also accounts for more than half the total membrane in eukaryotic cells
29
What is the surface differences between rough ER and smooth ER?
Smooth ER lacks ribosomes embedded in its walls Rough ER has surfaces with ribosomes embedded in them
30
What does the Smooth ER do?
Synthesize lipids Detoxify drugs and poisons Stores calcium ions
31
What does the Rough ER do?
Ribosomes secrete glycoproteins (proteins covalently bonded to carbohydrates) Distributes transport vesicles, secretory proteins surrounded by membranes A membrane factory for the cell
32
What is the Golgi apparatus?
Consists of flattened membranous sacs called cisternae Modifies products of the ER Manufactures certain macromolecules Sorts and packages materials into transport vesicles
33
What are the sides of the Golgi apparatus?
Cis face: "Receiving" side of Golgi apparatus Trans face: "shipping" side of Golgi apparatus
34
What is a lysosome?
A membranous sac of hydrolytic enzymes that digest macromolecules Work best in acidic environment inside the lysosome Hydrolytic enzymes and lysosomal membranes made by rough ER and transferred to G.A
35
What do lysosomes do?
Some cells engulf others by phagocytosis, forming food vacuoles A lysosome fuses with the vacuole and digests the contents Lysosomes use enzymes to recycle the cell's own organelles and macromolecules, called autophagy
36
What are vacuoles?
Large vesicles derived from the ER and G.A Performs a variety of functions in different kinds of cells
37
What are the kinds of vacuoles?
Food vacuoles formed by phagocytosis Contractile vacuoles are found in freshwater protists, and pump excess water out of cells Central vacuoles are found in mature plant cells, and contain a solution called sap
38
What does a central vacuole do?
It's the plant's main repository of inorganic ions, which includes potassium and chloride Also plays a major role in plant cell growth (turgor pressor)
39
What does the mitochondria do?
The sites of cellular respiration (metabolic process that uses oxygen to generate ATP) Endosymbiont theory Enveloped in double membrane Contains free ribosomes and circular DNA molecules Grows and reproduces somewhat independently in cells
40
What are chloroplasts?
The site of photosynthesis in photosynthetic cells Enveloped by a double membrane Contains free ribosomes and circular DNA molecules Grows and reproduces somewhat independently in cells
41
Characteristics of mitochondria?
Found in nearly all eukaryotic cells Smooth outer membrane, inner membrane folded into cristae Inner membrane in two compartments: intermembrane space and mitochondrial matrix Some metabolic steps of cellular respiration are catalyzed in the mitochondrial matrix
42
Characteristics of chloroplasts?
Contain green pigment chlorophyll Contains enzymes and other molecules that function in photosynthesis Found in leaves and other green organs of plants and in algae
43
What do chloroplasts contain?
Thylakoids, which are membranous sacs that are stacked to form grana (um) Stroma, which is the internal fluid It is also part of a group of plant organelles called plastids
44
What are peroxisomes?
Specialized metabolic compartments bound by a single membrane Contain enzymes that remove hydrogen atoms from various substances and transfer them to oxygen; forms hydrogen peroxide
45
What do the peroxisomes do?
Some use oxygen to break fatty acids into smaller molecules for fuel for respiration In livers, they detoxify alcohol and other harmful compounds Glyoxysomes in fat storing tissues of plant seeds convert fatty acids to sugar to feed the emerging seedling
46
What is the cytoskeleton?
A network of fibers extending throughout the cytoplasm Its composed of three types of molecular structures: microtubules, microfilaments, intermediate filaments
46
What does the cytoskeleton do?
Organizes the cell's structures and activities, anchoring organelles Helps to support the cell and maintain its shape Interacts with motor proteins to produce cell motility- which cells use to travel along tracks provided by cytoskeleton
47
What are microtubules?
Thickest of the three cytoskeleton components; hollow tubes Made of tubulin polymers, a dimer
48
What do microtubules do?
Helps maintain cell shape Helps with cell motility Chromosome movements in cell division Organelle movements
49
What are microfilaments?
Two intertwined strands of actin Made of actin proteins
50
What do microfilaments do?
Help maintain cell shape Changes in cell shape Muscle contractions Cytoplasmic streaming (plant cells) Cell motility Cell division (animal cells)
51
What are intermediate filaments?
Fibrous proteins coiled into cables Can be one of several different proteins, including keratins The "permanent" one out of the three
52
What do intermediate filaments do?
Helps maintain cell shape Anchorage of nucleus and certain other organelles Formation of nuclear lamina
53
What are centrosomes/centrioles?
Animal cells: microtubules grow out from a centrosome near the nucleus, which has a pair of centrioles with nine triplets of microtubules arranged in a ring
54
What do cilia/flagella do?
Microtubules control the beating of flagella/cilia Many unicellular protists locomote with them, but multicellular cells can have them as well Motile cilia are in larger numbers on cell surfaces; flagella are limited to only a few or one
55
Commonalities between cilia and flagella?
A group of microtubules sheathed in an extension of the plasma membrane Nine doublets of microtubules are arranged in a ring with two single microtubules in the center Basal body that anchors the cilia/flagella Motor proteins called dynein that drive the bending movements of the structures
56
What is dynein?
A motor protein that walks along microtubules The movements of the "feet" cause the microtubules to bend instead of slide, because the tubules are held in place
57
What are the differences of microfilaments in motile structures?
They contain the protein myosin along with actin
58
What is cytoplasmic streaming?
A circular flow of cytoplasm within cells that is driven by actin protein interactions
59
Characteristics of cell walls in plant cells?
Prokaryotes, fungi, and some protists have them as well Cell walls protect the plant cell, maintain shape, and prevent excessive uptake of water Made of cellulose fibers embedded in other polysaccharides and protein
60
Layers of a cell wall?
Primary cell wall Middle lamella Secondary cell wall
61
What is the primary cell wall?
It is a relatively thin and flexible wall, the membrane that is secreted first during the cell's "infancy"
62
What is the middle lamella?
A thin layer between primary walls, and contains polysaccharides called pectins
63
What is a secondary cell wall?
Found in some cells; is added between the plasma membrane and the primary cell wall
64
What is the extracellular matrix (ECM)?
Animal cell equivalent of cell walls Made of glycoproteins like collagen, proteoglycans, and fibronectin Fibronectin and other proteins bind to receptor proteins in the plasma membrane called integrins
65
What does the ECM do?
Can regulate a cell's behavior by communicating with a cell through integrins Can influence the activity of genes in the nucleus Mechanical signaling may occur through cytoskeleton changes that trigger chemical signals in the cell
66
What are cell junctions?
Neighboring cells in tissues/organs/systems adhere, interact, and communicate through direct physical contact
67
What are plasmodesmata?
Channels that connect plant cells Water and small solutes (sometimes proteins and RNA) can pass from cell to cell
68
What are the types of cell junctions?
Tight junction Desmosomes Gap junctions
69
What are tight junctions?
Membranes of neighboring cells are pressed together and prevent leakage of extracellular fluid (skin)
70
What are desmosomes?
Also called anchoring junctions, they fasten cells together into strong sheets (heart cells)
71
What are gap junctions?
Also called communicating junctions, they provide cytoplasmic channels between adjacent cells
72
What are some of the embedded proteins in a cell's membrane?
Proton pump Calcium channel Aquaporin Receptor

General Bio 1 for science majors (11 decks)

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