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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
Q

Describe the Golgi apparatus and its role

A

flattened sacs and vesicles

  • concentrates, packages and stores protiens
  • site of polysaccharide synthesis for cell wall
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26
Q

What are the 3 regions of the golgi apparatus

A

Cis, medial and trans

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27
Q

Where do primary lysosomes originate and what do they contain

A 
From golgi apparatus
Contain hydrolases (digestive enzymes) that hydrolaze macromolecules into monomers
28
Q

How to Secondary lysosomes form?

A

Form when primary lysosomes fuse with phagosome containing macromolecules from outside the cell
Enzymes in the secondary lysosome hydrolyze the food molecules

29
Q

What are phagocytes

A

specialised cells that take in and break down materials

30
Q

What is Autophagy

A

programmed destruction of cell parts within a lysosome

31
Q

What organelles do cells gain energy from?

A

Mitochondria or chloroplasts (plants)

32
Q

Describe the structure of mitohondria

A

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
Q

What cell types containt plastids and what are they used for

A

Plants and algae cells
some are used for torage
e.g. chloroplasts contain chlorophyl (site of photosynthesis)

34
Q

What type of process is photosynthesis?

A

Anabolic

35
Q

What is the structure of chloroplasts

A

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
Q

What are other common plastids?

A

Chromoplasts - make and store yellow, red and orange pigments
Leukoplasts - store macromolecules

37
Q

What is the role of peroxisomes?

A

collect and break down toxic by-products of metabolism

38
Q

WHat is the role of glyoxosomes and what cell type contains them

A

Found in plant cells

where lipids are converted to carbohydrates for growth

39
Q

What are the functions of vacuoles

A

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
Q

What is the function of contractile vacuoles

A

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
Q

What is the function of the cytoskeleton?

A

support and maintain cell shape
hold or move organelles
cytoplasmic streaming
anchors cell in shape (with extracellular structures)

42
Q

What are the 3 components of the cytoskeleton

A

microfilaments
intermediate filaments
microtubules

43
Q

What do microfilaments do?

A

Movement of cell or cell parts

determine and stabilise cell shape

44
Q

What are microfilaments made of

A

Atin monomers

45
Q

What is dynamic instability and what is its role?

A

Shortening or lengthening of microfilaments or microtubules

Allows fast assembly or breakdown of cytoskeleton

46
Q

What are motor proteins?

A

any protein that causes movement in a cell

47
Q

What are the properties of intermediate fillaments?

A

> 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
Q

What are the properties of microtubules?

A

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
Q

What are microtubules made from

A

chains of dimers of protein (tubulin) surrouding a hollow core

50
Q

What are the results of polymerization and depolymerization of microtubules?

A

Polymerization = rigid structure

Depolymerization = collapse

51
Q

What are the differences between cilia and flagella?

A

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
Q

What is Dynein?

A

Motor protein tha changes shape and drives sliding of doublets in flagella

53
Q

What is Nexin?

A

protein that crosslinks doublets and revents sliding (so cilia bend)

54
Q

Describe the arrangement of microtubules in cilia and flagella

A

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
Q

What methods are used to determine the link between structure (A) and function (B) of cytoskeleton

A

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
Q

What components make up extracellular structures in eukaryotic cells?

A

Fibrous macromolecule
Gel-like medium in which fibres are embedded
(these are excreted out of the cell)

57
Q

What is the plant cell wall and what is it made of?

A

Semi-rigid structure outside the cell wall

  • Fibrous component is polysaccharide cellulose
  • Gel-like matrix contains cross-linked polysaccharides and proteins
58
Q

What are the roles of the plant cell wall

A

Support for he cell and limit volume by remaining rigid
Barrier to infection
Contributes to form during growth and development

59
Q

What is plasmodesmata?

A

cell mebrane-lined channels that connect adjacent plant cells
– allow movement of water, ions, small molecules, hormones and some RNA and proteins

60
Q

Many animal cells are surrounded by an extracellular matrix. What is this made of?

A

Fibrous component- collagen
Gel-like matrix - proteoglycans
A third group of proeins links collagen and matrix

61
Q

What is the funciton of extracellular matrix in animals

A

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
Q

How do proteins connect extracellular matrix to the cell membrane?

A

bind to microfilaments in the cytoplasm and to collagen fibres in extracellular matrix.
Proteins change shape and detach from colllagen for cell movement

63
Q

What are the three types of cell junctions

A

Tigh junctions
Desmosomes
Gap junctions

64
Q

What is the role of tight junctions?

A

prevent substances from moving through space in cells

65
Q

What is the role of desmosomes

A

connect cells, allow movement in matrix

66
Q

What is the role of gap junctions

A

channels between membrane pores in adjacent cells, allow substances to pass quickly between cells

Biological Systems (20 decks)

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