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Biological Systems > Chapter 4 Cells > Flashcards

Chapter 4 Cells Flashcards

1
Q

What is the significance of the Surface area to volume ratio of a cell?

A

Volume determines metabolic activity
Surface area determines excretion and absorption
Larger cells have increased waste production and increased need for nutrient absorption, but decreased surface area for that to occur

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2
Q

What are the two types of microscopes used to see cells? What resulution can the see?

A

Light microscope - 0.2um

Electron microscope - 2nm

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3
Q

What is the first step in chemical analasys of cells?

A

breaking them open to make cell-free extract (which has the same properties as the cell)
Cell structures can then be separated by size in a centrifuge

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4
Q

What is the role of the cell membrane?

A

Selectively permeable barrier. Helps maintain homeostasis, role in communication and may contain proteins for binding to adjacent cells.

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5
Q

What are the two types of cells and their differences

A

Prokaryotic - no membrane enclosed compartments (organelles)

Eukaryotic - membrane enclosed compartments (organelles) such as the nucleus

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6
Q

Where do prokaryotic cells contain their DNA?

A

In the nucleoid region.

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7
Q

What does the cytoplasm of prokaryotic cells contain?

A

ribosomes and cytosol (water and dissolved materials) and suspended particles.

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8
Q

Most prokaryotic cells have a rigid cell wall - what do bacterial cell walls contain?

A

peptidoglycans

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9
Q

What external structures do some bacteria cells containt

A

Most have rigid cell wall
Some have additional outer membrane that is permeable
Others have slimy layer of polysaccharides (capsule)

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10
Q

What is the structure some prokaryotes use to swim and what is it made of?

A

Flagella - made of flagellin

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11
Q

What is the cytoskeleton?

A

Filaments of polymer and monomer subunits that play a role in cell division and cell shape. - Helical actin-like protein.

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12
Q

What structures do eukaryotic cells contain?

A

Cell membrane, cytoplasm, ribosomes and membrane enclosed organelles

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13
Q

What is the role of ribosomes in the cell?

A

Present in eukaryotic cells and prokaryotic cells - they translate nucleotide sequence of RNA into polypeptides (proteins)

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14
Q

What do ribosomes consist of?

A

One large and one small subunit that consist of ribosomal RNA bound to small protein molecules.

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15
Q

Where are ribosomes found in the cell?

A

Either in the cytoplasm or, in Eukaryotic cells, attached to RER or mitochondria

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16
Q

What is the role of the nucleus?

A

Holds DNA and site of DNA replication
Where DNA is transcribed to RNA
Contains the nucleolus - where ribosomes form RNA and proteins begin

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17
Q

What makes up chomosomes?

A

DNA and Chromatin

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18
Q

What makes up the endomembrane system?

A

Nuclear envelope, ER, golgi apparatus and lysosomes

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19
Q

What is the nuclear envelope?

A

two membranes that separate nucleus from cytoplasm. Control the movement of molecules via pores.

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20
Q

How are substances transported between parts of the endomembrane system?

A

In membrane surrounded vesicles

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21
Q

What is the Endoplasmic Reticulum and what are the 2 types?

A

Network of interconnected membanes in the cytoplasm with large surface area.
Rough ER
Smooth ER

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22
Q

What is the role of RER?

A

proteins are chemically modified (folded into tertiary structure) and tagged for delivery to specific areas
All secreted proteins and most membrane proteins pass through RER

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23
Q

What are glycoproteins and what is their role?

A

proteins linked to carbohydrate groups

Important in cell recognition and interractions

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24
Q

What it he role of SER?

A

chemically moifies small molecules (Drugs and pesticides), site of glycogen degranulation, site of lipid and steroid synthesis and storage site for calcium ions.

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25
Describe the Golgi apparatus and its role
flattened sacs and vesicles - concentrates, packages and stores protiens - site of polysaccharide synthesis for cell wall
26
What are the 3 regions of the golgi apparatus
Cis, medial and trans
27
Where do primary lysosomes originate and what do they contain
``` From golgi apparatus Contain hydrolases (digestive enzymes) that hydrolaze macromolecules into monomers ```
28
How to Secondary lysosomes form?
Form when primary lysosomes fuse with phagosome containing macromolecules from outside the cell Enzymes in the secondary lysosome hydrolyze the food molecules
29
What are phagocytes
specialised cells that take in and break down materials
30
What is Autophagy
programmed destruction of cell parts within a lysosome
31
What organelles do cells gain energy from?
Mitochondria or chloroplasts (plants)
32
Describe the structure of mitohondria
2 membranes Outer is very porous Inner is made of extensive folds (Christae) that incresase surace area Between membranes is fluid filled matrix holding enzymes DNA and ribosomes
33
What cell types containt plastids and what are they used for
Plants and algae cells some are used for torage e.g. chloroplasts contain chlorophyl (site of photosynthesis)
34
What type of process is photosynthesis?
Anabolic
35
What is the structure of chloroplasts
2 membranes and internal membrasnes called thylakoids Internal structures are - Granum - stack of thylakoids (where light energy is converted to chemical energy) - Stroma (aqueous matrix around grana, contain ribosomes and DNA. Site of carbohydrate synthesis)
36
What are other common plastids?
Chromoplasts - make and store yellow, red and orange pigments Leukoplasts - store macromolecules
37
What is the role of peroxisomes?
collect and break down toxic by-products of metabolism
38
WHat is the role of glyoxosomes and what cell type contains them
Found in plant cells | where lipids are converted to carbohydrates for growth
39
What are the functions of vacuoles
Mainly found in plant and fungi cells, functions are: - Storage of waste and toxic compounds - create turgor pressure to maintain cell shape - Reproduction - contain pigments in flowers and fruit to attract pollinators - Catabolism - digestive enzymes in seed vacuoles hydrolyze stored food for early growth
40
What is the function of contractile vacuoles
In freshwater protists get fird of excess water entinering the cell due to solute imbalance - let water in then quickly contract to expel water through special pores
41
What is the function of the cytoskeleton?
support and maintain cell shape hold or move organelles cytoplasmic streaming anchors cell in shape (with extracellular structures)
42
What are the 3 components of the cytoskeleton
microfilaments intermediate filaments microtubules
43
What do microfilaments do?
Movement of cell or cell parts | determine and stabilise cell shape
44
What are microfilaments made of
Atin monomers
45
What is dynamic instability and what is its role?
Shortening or lengthening of microfilaments or microtubules | Allows fast assembly or breakdown of cytoskeleton
46
What are motor proteins?
any protein that causes movement in a cell
47
What are the properties of intermediate fillaments?
>50 kinds in 6 molleculat classes - tough, ropelikee proein assemblage that are more permanent than other filaments. Anchor cell structures in place Resist tension, maintain rigidity
48
What are the properties of microtubules?
Thickest cytoskeletal elements form rigid internal skeleton for some cells or regions and act as framework for motor proteins to move structures in cells
49
What are microtubules made from
chains of dimers of protein (tubulin) surrouding a hollow core
50
What are the results of polymerization and depolymerization of microtubules?
Polymerization = rigid structure Depolymerization = collapse
51
What are the differences between cilia and flagella?
Cilia - short, many present.. Move cell or substaces aong cell surface Flagella - longer, fewer present (1 or 2), push or pull cell through wwater
52
What is Dynein?
Motor protein tha changes shape and drives sliding of doublets in flagella
53
What is Nexin?
protein that crosslinks doublets and revents sliding (so cilia bend)
54
Describe the arrangement of microtubules in cilia and flagella
9+2 pattern Made of doublets (9 fused pairs of microtubules that form a cylinder) and one unused pair in the centre Movement occurs as doublets slide past each other
55
What methods are used to determine the link between structure (A) and function (B) of cytoskeleton
Inhibition: use of drug to inhibit A, if B occurs, A does not cause B Mutation: if genes for A are missing and B does no occur, A probably causes B
56
What components make up extracellular structures in eukaryotic cells?
Fibrous macromolecule Gel-like medium in which fibres are embedded (these are excreted out of the cell)
57
What is the plant cell wall and what is it made of?
Semi-rigid structure outside the cell wall - Fibrous component is polysaccharide cellulose - Gel-like matrix contains cross-linked polysaccharides and proteins
58
What are the roles of the plant cell wall
Support for he cell and limit volume by remaining rigid Barrier to infection Contributes to form during growth and development
59
What is plasmodesmata?
cell mebrane-lined channels that connect adjacent plant cells -- allow movement of water, ions, small molecules, hormones and some RNA and proteins
60
Many animal cells are surrounded by an extracellular matrix. What is this made of?
Fibrous component- collagen Gel-like matrix - proteoglycans A third group of proeins links collagen and matrix
61
What is the funciton of extracellular matrix in animals
Holds cells together in tissues Contribute to physical properties of cartilage, skin, bone and other tissues Help filter materials (kidneys) Orient cell movement during development and tissue repair
62
How do proteins connect extracellular matrix to the cell membrane?
bind to microfilaments in the cytoplasm and to collagen fibres in extracellular matrix. Proteins change shape and detach from colllagen for cell movement
63
What are the three types of cell junctions
Tigh junctions Desmosomes Gap junctions
64
What is the role of tight junctions?
prevent substances from moving through space in cells
65
What is the role of desmosomes
connect cells, allow movement in matrix
66
What is the role of gap junctions
channels between membrane pores in adjacent cells, allow substances to pass quickly between cells

Biological Systems (20 decks)

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