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Bio 1 (101-NYA-05) > Lecture 6 - The Cell I > Flashcards

Lecture 6 - The Cell I Flashcards

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1
Q

describe the cell

A

simplest self-replicating entity that can exist as an independent unit of life

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2
Q

what do all cells have?

A

stable blueprint of information in molecular form (DNA)

  • discrete boundary that separates the interior of the cell from its external environment
  • ability to harness materials and energy from the environment
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3
Q

plasma membranes function

A
  • physically separate the inside and outside of the cells

- create compartments within the cell (organelles/vacuoles/vesicles)

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4
Q

plasma membranes structure

A
  • lipids
  • proteins
  • carbohydrates (glycolipids and glycoproteins)
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5
Q

what types of cells have plasma membranes

A

prokaryotic and eukaryotic

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6
Q

what are plasma membranes composed of

A

phospholipids

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7
Q

are membranes fluid?

A

yes

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8
Q

the phospholipids that form plasma membranes can do what type of movements

A
  • turn on their axis
  • move laterally in any direction over the surface of the membrane
  • flipping across the membrane (inside to out) occurs very rarely
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9
Q

what happens to plasma membranes when the temperature lowers

A
  • membranes go from a fluid state to a solid state

- temperature at which a membrane solidifies depends on types of lipids

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10
Q

in what state must plasma membranes be to work properly

A
  • membranes must be fluid to work properly; they are usually about as fluid as oil
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11
Q

what is plasma membrane fluidity affected by?

A
  • type of fatty acid chain

- presence of cholesterol

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12
Q

effect of type pf fatty acid chain on membrane fluidity

A
  • membranes rich in unsaturated fatty acids are more fluid than those rich in saturated fatty acids
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13
Q

effect of the presence of cholesterol on membrane fluidity

A
  • effect depends on temperature
  • cholesterol reduces membrane fluidity at moderate temperatures by reducing phospholipid movement, but at low temperatures it hinders solidification by disrupting the regular packing of phospholipids
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14
Q

How could a cell change its membrane in response to very cold temperatures?

A

the type of fatty acid in phospholipids would be unsaturated

there would be lots of cholesterol

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15
Q

what is a membrane (made of)

A

a collage of different proteins, often grouped together, embedded in fluid matrix of lipid bilayer

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16
Q

what do membrane proteins do

A

determine most of the membrane’s specific functions

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17
Q

name types of membrane proteins

A
  • integral membrane proteins

- peripheral membrane proteins

18
Q

integral membrane proteins

A
  • go from the outside of the membrane (go through it)
  • composed of three regions: 2 hydrophilic and one hydrophobic region
  • permanently associated with the cell membrane
19
Q

peripheral membrane proteins

A
  • temporarily associated with integral membrane proteins through weak noncovalent interactions (H-bonds) (on outside)
  • easily separated from the membrane
  • play a role in transmitting information received from external signals
20
Q

membrane carbohydrates (include glycolipids and glycoproteins)

A
  • involved in cell to cell recognition
  • located outside of membrane
  • glycolypids: carbs covalently bonded to lipids
  • glycoproteins: carbs covalently bonded to proteins
21
Q

fluid mosaic model

A

describes cell membranes:

  • plasma membranes are fluid because of phospholipids and cholesterol
  • plasma membranes are described as a mosaic because of the proteins, glycoproteins and glycolipids embedded within the membrane
22
Q

plasma membranes function

A
  • separate the inside from the outside of the cell
  • maintains homeostasis (the active maintenance of the constant environment)
  • exhibits selective permeability, allowing some substances to cross it more easily than others
23
Q

the cell wall (location)

A

found outside of the plasma membranes of prokaryotic cells as well as those of plant and fungal cells

24
Q

cell wall (function)

A
  • provides structural support and protection

- resists expansion and allows pressure (turgor pressure) to build up in a cell when it absorbs water

25
Q

turgor pressure

A

force exerted by water pressing against an object

provides structural support

26
Q

cell wall structure

A
  • rigid structure made or carbohydrates and proteins that surrounds the plasma membrane
27
Q

what are the following types of cell walls made of

  • plant
  • fungi
  • bacteria
A
  • plant - polysaccharides (ex cellulose)
  • fungi - polysaccharides (ex. chitin)
  • bacteria - glycoprotein (peptitoglycan)
28
Q

name cell adhesion types

A
  • tight junction
  • desmosome
  • gap junction
29
Q

tight junction

A
  • prevent leakages of extracellular fluid across a layer of epithelial cells by forming continuous seals around the cells
  • tight junctions between skin cells make us watertight
30
Q

desmosome

A
  • function live RIVETS, fastening cells together in strong sheets
  • intermediate filaments anchor desmosomes together
  • attach muscle cells to each other
31
Q

gap junction

A

provide cytoplasmic channels from one cell to an adjacent cell

32
Q

extracellular matrix overview

A

provides molecular framework that ultimately determines the structural architecture of plants and animals

in both plants and animals, contributes to structural support and provides informational cues that determine the activity of the cells.

33
Q

ECM of animals

A
  • found in most tissues (abundant in connective tissue)

- mainly composed of glycoproteins and tiher carbohydrate-containing “fibrous” molecules (elastin and collagen)

34
Q

how are collagen and other fibers involved in ECM of animals

A

they’re embedded in a network woven out of proteoglycans secreted by cells (fibroblasts)

35
Q

how are cells attached to ECM

A

by special ECM glycoproteins, such as fibronectin

36
Q

fibronectin is bound to what

A

bound to cell-surface receptor proteins called integrins, that are built into the plasma membrane

37
Q

within cytoplasms, integrins are bound to _______.

A

microfilaments

38
Q

integrins transmit signals between what

A

the ECM and the cytoskeleton and thus integrate changes occurring outside and inside the cell

39
Q

by communicating through integrins, what can the ECM do?

A

the ECM can regulate a cell’s function, structure, and behaviour

  • the integrins recieve a signal and transmit it to the nucleus via microfilaments
  • this may trigger signaling pathways inside the cell and nucleus that lead to changes in the set of proteins being synthesized
40
Q

what is the path of a signal being sent from one cell to another

A

nucleous -> cytoskeleton (microfilaments) -> integrins -> fibronectin -> collagen

(opposite path is for receiving signal from outside cell)

41
Q

why are most cells small?

A

due to reliance on diffusion of substances in and out of cells

cells work all the time, constantly performing chem reactions, thus need energy and to remove all waste produced

bc of requirements for homeostasis
metobolic demands are determined by volume but transport of materials is determined by surface area

cells require sufficient area to support cell’s metabolic needs, keeps cell small

42
Q

where do materials pass in and out

A

cell surface

Bio 1 (101-NYA-05) (8 decks)

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