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DAT Prep > Cells and Organelles > Flashcards

Cells and Organelles Flashcards

1
Q

What are cell membranes?

A

Hold cellular contents ad are made up of phospholipids, cholesterol, and proteins.

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2
Q

Why are phospholipids amphipathic?

A

Because the molecules have polar and nonpolar parts allowing them to form a lipid bilayer in an aqueous environment.

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3
Q

How does cholesterol contribute to cell function?

A

Amphipathic and helps regulate membrane fluidity.

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4
Q

What are membrane proteins?

A

Either integral or peripheral membrane proteins

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5
Q

What are Integral proteins?

A

Traverse the entire bilayer, so they must be amphipathic. Their nonpolar parts lie in the middle of the bilayer while their polar ends extend out into the aqueous environment cell signaling or transport.

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6
Q

What are peripheral membrane proteins?

A

Found on the outside of the bilayer and are hydrophilic.

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7
Q

What are Receptors?

A

Trigger secondary responses withing the cell signaling

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8
Q

What is Adhesion?

A

Attaches cells to other things and act as anchors for the cytoskeleton

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9
Q

What is cellular recognition?

A

Proteins which have carbohydrate chains (glycoproteins) used by cells to recognize other cells

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10
Q

What is the fluid mosaic model?

A

Describes how the components that make up the cell membrane can move freely within the membrane

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11
Q

How can fluidity be affected?

A

Temperature, cholesterol, and degrees of unsaturation

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12
Q

What are crossing cell membranes?

A

Cells must regulate the traveling of substances across the cell membrane

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13
Q

What is simple diffusion?

A

Flow of small, uncharged nonpolar substances across the cell membrane, down their concentration gradient (high to low) with no energy.

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14
Q

What is Osmosis?

A

A type of simple diffusion that involves water. Water is polar but it is small enough to cross the membrane.

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15
Q

What is facilitated transport?

A

Integral proteins allow larger hydrophilic molecules to cross the cell membrane.

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16
Q

What are the uniporters in facilitated transport?

A

Single substance, single direction

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17
Q

What are symporters?

A

Two substances, same direction

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18
Q

What are antiporters?

A

Two substances, opposite directions

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19
Q

What are channel proteins?

A

An open tunnel that faces both sides of the bilayer and carrier proteins binds to a moleule on one side and changes shape to bing it to the other side.

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20
Q

What is passive diffusion?

A

A type of facilitated transport that is performed by channel proteins bringing molecules down their concentration gradient without energy use but a protein channel is used.

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21
Q

What is active transport?

A

The substance travels against their concentration gradient and requires energy by carrier proteins.

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22
Q

What is the primary active transport?

A

Uses ATP hydrolysis to pump molecules against their concentration gradient. EX. Sodium-potassium transport pump.

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23
Q

What is the secondary transport?

A

Uses free energy, released when other molecules flow down their concentration gradient pump the molecule across the membrane.

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24
Q

What is cytosis?

A

refers to the bulk transport of large polar/hydrophilic molecules across the cell membrane and requires energy

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25
Q

What is Endocytosis?

A

Involved the cell membrane wrapping around an extracellular substance internalizing via vesicle or vacuole
Ex. Phagocytosis: Cellular eating around solid objects
Pinocyotisis: Cellular drinking around dissolved materials
Receptor-mediated endocytosis: requires the binding of dissolved molecules to peripheral membrane receptor proteins which initiates endocytosis.

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26
Q

What is exocytosis?

A

is the opposite of endocytosis, releasing material to the extracellular environment through vesicle secretion.

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27
Q

What are organelles?

A

cellular components enclosed by phospholipids bilayers. They are located within the cytosol and together make up the cytoplasm.

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28
Q

What do Eukaryotic cells contain that prokaryotes do not??

A

membrane-bound organelles. Prokaryotes used genetic material to keep material in a region called nucleoid.

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29
Q

The function of nucleus?

A

To protect and house DNA. DNA replication and transcription occur here (DNA to mRNA).

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30
Q

What is the nucleoplasm?

A

is the cytoplasm of the nucleus.

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31
Q

What is the nuclear envelope?

A

is the membrane of the nucleus. It contains two phospholipid bilayers (inner and outer) with a perinuclear space in the middle.

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32
Q

What are nuclear pores?

A

Holes in the nuclear envelope that allow molecules to travel in and out of the nucleus.

33
Q

What are nucleur lamina?

A

It provides structural support to the nucleus as well as regulating DNA and cell division.

34
Q

What is the nucleolus?

A

A dense area that is responsible for making rRNA and producing ribosomal subunits (rRNA to proteins).

35
Q

What are ribosomes?

A

are not organelles but work as small factories that carry out the translation. (mRNA to protein).

36
Q

What are the subunits for Eukaryotic ribosomal subunits?

A

60s and 40s. (nucleoplasm) The complete ribosome in the cytosol is 80s.

37
Q

What are the subunits for Prokayotic ribosomal subunits?

A

50s and 30s. (nucleiod) The complete ribsome in the cytosol is 70s.

38
Q

What is the rough ER?

A

It is continuous with the outer membrane of the nuclear envelope and is rough because it is embedded with ribosomes. Proteins synthesized by the embedded ribosomes are sent into the lumen.

39
Q

What is the smooth ER?

A

Not continuous with other membranes. The main function is to synthesize lipids and produce steroid hormones and detoxify cells.

40
Q

What is the Golgi apparatus?

A

made up of cisternae that modify and package substances. Vescicles come from the ER and reach the cis face of the golgi apparatus. Vesicles lease the golgi appartus from the trans face.

41
Q

What are lysosomes?

A

membrane bound organells that break down substances. (hydrolysis) contain acidic digestive enzymes that function at low pH they are carry out autophagy (recycling) and apoptosis (cell death).

42
Q

Function of transport vacuoles?

A

tranport materials between organelles.

43
Q

Function of food vacuoles?

A

hold endocytosed food and later fuse lysosomes

44
Q

Function of central vacuoles?

A

have a specialized membrane called the tonoplast, used for storage and material breakdown.

45
Q

Function of storage vacuoles?

A

store starches, pigments, toxics.

46
Q

Function of contractile vacuoles?

A

found in single-celled organisms and works to pump out excess water.

47
Q

Function of peroxisomes?

A

perform hydrolysis and break down fatty acids and help with detoxification these processes generate hydrogen peroxide which is toxic since it can produce reactive oxygen species (ROS). ROS can damage cells through free radicals. Peroxisomes contain an enzyme called catalase, breaks down hydrogen peroxide to water and oxygen.

48
Q

Function of mitochondira?

A

powerhouse of the cell

49
Q

Function of chloroplast?

A

found in plants and some protists carry out photosynthesis.

50
Q

Function of centrosomes?

A

Found in animals containing a pair of centrioles

51
Q

Function of microfilaments?

A

The smallest and are composed of a double helix of two actin filaments. Involved in cell movement. It can disassemble and assemble.

52
Q

What is cyclosis?

A

Stirring of cytoplasm: organelles and vesicles travel on microfilament tracks.

53
Q

What is cleavage furrow?

A

during cell division, actin microfilaments form contractile rings that split the cell.

54
Q

What is muscle contraction?

A

Actin microfilaments have directionality allowing myosin motor proteins to pull on them for muscle contraction.

55
Q

What are intermediate filaments?

A

between microfilaments and microtubules in size. More stable than microfilaments help with structural support. Ex. Keratin for hair and nails.

56
Q

What are microtubules?

A

Largest in size gives structural integrity to cells. Hollow and have walls made of tubulin protein dimers. Functions in cell division, cilia and flagella.

57
Q

What are centrioles?

A

Hollow cylinders made of nine triplets of microtubules. Centrosomes have a pair of centrioles. Replicate during the D phase of the cell cycle. So each daughter cell after cell division has one centrosome.

58
Q

What are Cilia and flagella?

A

have nine doublets of microtubules with two singles in the center. Produced by basal body.

59
Q

What is the extracellular matrix?

A

provides support between cells.

60
Q

What is proteglycan?

A

type of glycoprotein that has a high proportion of carbohydrates.

61
Q

What is collagen?

A

Most common structural protein and organized into collagen fibrils.

62
Q

What is integrin?

A

Transmembrane protein that facilitates ECM adhesion and signals to cells how to respond to the extracellular environment.

63
Q

What is fibronectin?

A

Protein that connects integrin to ECM and helps with signal transduction

64
Q

What is laminin?

A

Behaves similar to fibronecting, influence cell differentiation, adhesin and movement.

65
Q

What are cell walls?

A

carbohydrates based structures that acts like substitute provide structural support to cells that have or don’t ECM, present in plants bacteria and archaea.

66
Q

What is glycocalyx?

A

Glycolipid/glycoprotein coat found on bacterial and animal epithelial cells. Helps with adhesion, protection and cell recognition

67
Q

What are focal adhesions?

A

ECM connects via integins to actin microfilaments inside the cell.

68
Q

What are hemidosmosomes?

A

ECM connects via integrins to intermediate filaments inside the cell.

69
Q

What are tight junctions?

A

Form watertight seal between cells to ensure substances pass through cells not between them.

70
Q

What are the desmosomes?

A

Provide support against mechanical stress connects neighboring cells via intermediate filaments.

71
Q

What are adherens junctions?

A

Similar in structure and function to desmosomes, but connects neighboring cells via actin microfilaments.

72
Q

What are gap junctions?

A

Allow passage of ions and small molecules between cells.

73
Q

In-plant cells, what is the middle lamella?

A

Sticky cement is similar in function to tight junctions.

74
Q

In-plant cells, what are plasmodesmata?

A

cellular components enclosed by phospholipids bilayers. They are located within the cytosol and together make up the cytoplasm.

75
Q

What is isotonic solutions?

A

Same solute concentration as cells placed in them.

76
Q

what is hypertonic?

A

Higher solute concentration than the cells placed in them causing water to leave cell, cell shrinks.

77
Q

What is hypotonic?

A

Lower solute concentration than cells placed in them, water enters the cell, cell swells.

78
Q

What is lysis?

A

Bursting of the cell when too much water is in them.

DAT Prep (2 decks)

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