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science notes > [bio] cells > Flashcards

[bio] cells Flashcards

1
Q

what is a cell?

A

a basic unit of structure and function. it is the simplest unit with all characteristics of life

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2
Q

what are phospholipids?

A

a major component of biological membranes

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3
Q

special thing about phospholipids in cell membranes?

A

made up of two layers of phospholipids - phospholipid bilayer

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4
Q

why is phospholipid bilayer?

A

phospholipid tail is hydrophobic, needs the hydrophilic head to be facing outwards in contact with the extra cellular fluid outside the phospholipid bilayer

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5
Q

why is the cell membrane fluid

A

phospholipids and proteins are not stationary but can move rapidly across the surface of the membrane

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6
Q

why is the cell membrane mosaic

A

many different protein molecules are randomly scattered and embedded throughout the phospholipid bilayer

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7
Q

why are cell membranes partially permeable?

A

due to the nature of the phospholipids, only small hydrophobic molecules can pass through the phospholipid bilayer. as such, for hydrophilic or water-soluble molecules are unable to pass through the cell membrane, transport proteins are required.

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8
Q

what do you mean by partially permeable?

A

cell membrane only allows certain substances to pass through it

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9
Q

functions of partially permeable cell membrane

A

it functions to separate and protects a cell from its surrounding environment and controls how substances move in and out of the cell

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10
Q

what does cytoplasm contain

A
  • cytosol
  • cytoskeleton
  • organelles
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11
Q

what is cytosol?

A

aqueous solution of essential ions, soluble proteins and soluble organic compounds such as sugars and amino acids

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12
Q

what is cytoskeleton?

A

network of protein fibres that give support, motility and regulation to the cell

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13
Q

what is organelles?

A

structures with specialised functions, suspended in the cytosol

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14
Q

what is cytoplasmic streaming

A

the movement of the fluid substance within a plant or animal cell

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15
Q

how does cytoplasmic streaming help?

A

aids in the transport of materials and organelles around the cell

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16
Q

structure of nucleus

A

largest organelle within the eukaryotic cell, usually spherical

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17
Q

what does the nucleus contains

A
  • nuclear envelope
  • nucleolus
  • dna
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18
Q

what does nuclear envelope do

A

separates nucleus from the cytoplasm

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19
Q

what does nucleolus do

A

synthesise ribosomes

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20
Q

where are nucleus found

A

in almost all eukaryotic cells, except matured red blood cells

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21
Q

function of nucleus

A
  • contains the hereditary material (dna)
  • controls activities of the cell
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22
Q

structure of rough endoplasmic reticulum

A

a system of flattened membrane-bound sacs

23
Q

how does it look under the microscope

A

appears “rough” under electron microscope because of the presence of ribosomes on its surface

24
Q

functions of rer

A

protein synthesis - polypeptide chain synthesised by the ribosomes will be folded in the rer

25
Q

structure of ser

A

consists of fine tubules

26
Q

function of ser

A
  • lipid synthesis
  • detoxification of drugs and poisons
  • storage and release of calcium ions
27
Q

structure of Golgi apparatus

A

consist of stacks of flattened membrane-bound sacs

28
Q

function of Golgi apparatus

A

chemically modifies products receive from the er and packages them, before sending them to destinations inside or out of the cell using vesicles

29
Q

structure of lysosomes

A

small, spherical vesicles surrounded by a single membrane

30
Q

what does lysosomes contain

A

hydrolysis enzymes such as lipases, proteases and nucleases

31
Q

functions of lysosomes

A
  • to digest materials made in the cell or take in from outside by phagocytosis (e.g. food vacuoles in Amoeba)
  • to digest worn-out organelles in the cell, a process known as autophagy
32
Q

structure of animal vacuoles

A

fluid-filled sac bound by a single membrane

33
Q

how are animal vacuoles formed?

A

either by the pinching-off part of the cell membrane
or by enlargement of a vesicle from the Golgi apparatus

34
Q

shape and size of animal vacuole?

A

usually relatively smaller and exists temporarily

35
Q

function of animal vacuoles?

A

food vacuoles: formed by phagocytosis. in the case of intracellular digestion by macrophages

36
Q

structure of plant vacuoles

A

enclosed by single, partially permeable membrane called the tonoplast

37
Q

where is plant vacuoles found?

A

in mature plant cells, the large central vacuole is permanent and occupy over 80% of the cell volume

38
Q

what is in the plant vacuole?

A

filled with cell sap, a solution of dissolved such as sugars, ions, waste products, and pigments

39
Q

function of plant vacuole

A
  • storage of nutrients such as protein storage in seeds and inorganic ions, e.g. K+ and Cl-
  • disposal sites for metabolic by-products that would endanger the cell if they accumulated in the cytosol
  • may contain pigment that colour the cell, e.g. red and blue pigments of petals to attract pollinators
40
Q

structure of mitochondria

A

rod-shaped or cylindrical, bounded by double membrane

41
Q

where is mitochondria found?

A

in plant and animal cells

42
Q

function of mtiochondria

A
  • involved in aerobic respiration
  • contains DNA
  • ATP is the “energy molecule” in living organisms
43
Q

where is mitochondria found abundant in?

A

metabolically active cells
- e.g. muscle and liver cells

44
Q

structure of chloroplast

A

bounded by a double membrane

45
Q

what does chloroplast contain?

A
  • chlorophyll
  • thylakoids and stroma
46
Q

function of chloroplast

A

site of photosynthesis

47
Q

structure of ribosomes

A

small, round structures found in all cells

48
Q

special thing about ribosomes?

A

may occur as free ribosomes suspended in the cytosol or bound to rough er

49
Q

functions of ribosome?

A
  • site of polypeptide synthesis
  • free ribosomes generally make proteins that will function within the cytosol
  • bound ribosomes generally make protein that are destined for insertion into membranes, for packaging within certain organelles such as lysosomes, or for export from the cell
50
Q

strucute of centrioles

A

small, hollow cylinders that occur in pairs

51
Q

where are centrioles found?

A

in animals cells only, not in plant cells

52
Q

function of centrioles

A

play a role in cell division in animal cells

53
Q

similarities of animal and plant cells

A

both contain:
- cell membrane
- mtiochondria
- nucleus
- cytoplasm

54
Q

differences between plant and animal cell

A

chloroplast:
- plant: chloroplasts are present in large number of photosynthetic cells
- animals: chloroplast are absent

centrioles:
- plant: centrioples are absent
- animals: centrioles are present

vacuole:
- plant: present as a single, large and central vacuole
- animal: vacuoles are small and numerous

science notes (13 decks)

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