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Biology DAT > Chapter 2 > Flashcards

Chapter 2 Flashcards

1
Q

What is the cell membrane?

A

The cell membrane is a selectively permeable barrier composed of a phospholipid bilayer with embedded proteins.

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2
Q

What is the function of the cell membrane?

A

It regulates the movement of substances in and out of the cell and plays a role in cell signaling and communication.

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3
Q

What is a phospholipid bilayer?

A

It possesses hydrophilic heads that form the exterior surfaces and hydrophobic tails that face inward, creating a barrier to most water-soluble substances.

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4
Q

What are membrane proteins?

A

Embedded within the phospholipid bilayer, they facilitate transport, act as receptors for signaling, and provide structural support.

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5
Q

What role do carbohydrates play in the cell membrane?

A

They are attached to proteins and lipids on the extracellular surface and play key roles in cell recognition, signaling, and adhesion.

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6
Q

What is the function of cholesterol in the cell membrane?

A

Cholesterol helps to stabilize membrane fluidity and is found within eukaryotic cell membranes.

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7
Q

What are integral proteins?

A

Integral proteins are embedded in the phospholipid bilayer and can function as receptors, channels, or carrier proteins for transport.

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8
Q

What are peripheral membrane proteins?

A

Peripheral membrane proteins are found on the surface of the bilayer and can function as receptors or assist with adhesion and cell recognition.

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9
Q

What is the fluid mosaic model?

A

It describes how the components of the cell membrane can move freely within the membrane and contain many different kinds of structures.

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10
Q

How does temperature affect cell membrane fluidity?

A

Higher temperatures increase fluidity while lower temperatures decrease it.

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11
Q

What is the role of cholesterol in membrane fluidity?

A

Cholesterol holds the membrane together at high temperatures and keeps it fluid at low temperatures.

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12
Q

How do saturated and unsaturated fatty acids affect membrane packing?

A

Saturated fatty acids pack more tightly than unsaturated fatty acids, which have double bonds that may introduce kinks.

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13
Q

What is the function of membrane proteins as receptors?

A

Transmit a signal to a cell and trigger secondary responses within the cell.

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14
Q

What are agonists?

A

Molecules that bind to receptors and functionally activate a target.

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15
Q

What are antagonists?

A

Molecules that bind to receptors and prevent other molecules from binding, inhibiting production of a response.

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16
Q

What is the adhesion function of membrane proteins?

A

Attach cells to other things (e.g., other cells) and act as anchors for the cytoskeleton.

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17
Q

What is the role of glycoproteins in cellular recognition?

A

Proteins with carbohydrate chains used by cells to recognize other cells.

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18
Q

What is the first type of transport across the cell membrane?

A

Simple diffusion: Diffusion of small uncharged molecules (e.g., O2, CO2, H2O) or lipid soluble molecules (steroids) directly across the cell membrane, down their concentration gradient (high to low) without using energy.

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19
Q

What is the second type of transport across the cell membrane?

A

Facilitated transport: Channel proteins allow the diffusion of large (e.g., glucose, sucrose) or charged molecules (e.g., Na+, K+, Cl-) across the cell membrane, down their concentration gradient without using energy.

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20
Q

What is the third type of transport across the cell membrane?

A

Active transport: Substances travel against their concentration gradient and require the consumption of energy by carrier proteins.

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21
Q

What is primary active transport?

A

Primary active transport uses ATP hydrolysis to pump molecules against their concentration gradient.

For example, the sodium-potassium (Na+/K+) pump sets a membrane potential.

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22
Q

What is secondary active transport?

A

Secondary active transport uses the energy from one molecule moving down its electrochemical gradient to drive the transport of another molecule against its concentration gradient. This requires an energy investment to establish the initial concentration gradient.

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23
Q

What is cytosis?

A

Cytosis refers to the bulk transport of molecules across the cell membrane.

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24
Q

What is endocytosis?

A

Endocytosis involves the cell membrane wrapping around an extracellular substance, internalizing it into the cell via a vesicle or vacuole.

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25
Q

What is phagocytosis?

A

Phagocytosis: Cellular eating around solid objects.

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26
Q

What is pinocytosis?

A

Pinocytosis: Cellular drinking around dissolved materials (liquids).

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27
Q

What is receptor-mediated endocytosis?

A

Receptor-mediated endocytosis: Requires the binding of dissolved molecules to peripheral membrane receptor proteins, which initiates endocytosis.

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28
Q

What role does clathrin play in endocytosis?

A

Clathrin is a protein that aids in receptor-mediated endocytosis by forming a pit in the membrane that pinches off as a coated vesicle.

This is known as clathrin-mediated endocytosis.

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29
Q

What is exocytosis?

A

Exocytosis is the opposite of endocytosis, in which material is released to the extracellular environment through vesicle secretion.

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30
Q

What are organelles?

A

Organelles are cellular compartments enclosed by phospholipid bilayers (membrane bound) located within the cytosol and help make up the cytoplasm.

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31
Q

Which type of cells contain membrane-bound organelles?

A

Only eukaryotic cells contain membrane-bound organelles.

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32
Q

What do prokaryotic cells lack?

A

Prokaryotic cells do not have membrane-bound organelles but have adaptations like a nucleoid for genetic material.

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33
Q

What is the primary function of the nucleus?

A

The nucleus primarily functions to protect and house DNA.

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34
Q

What occurs in the nucleus?

A

DNA replication and transcription (DNA → mRNA) occurs in the nucleus.

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35
Q

What is nucleoplasm?

A

The nucleoplasm is the cytoplasm of the nucleus.

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36
Q

What is the nuclear envelope?

A

The nuclear envelope is the membrane of the nucleus, containing two phospholipid bilayers (one inner, one outer).

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37
Q

What are nuclear pores?

A

Nuclear pores are holes in the nuclear envelope that allow molecules to travel in and out of the nucleus.

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38
Q

What is the function of the nucleolus?

A

The nucleolus is a dense area responsible for producing components of ribosomal subunits including rRNA (ribosomal RNA).

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39
Q

Are ribosomes considered organelles?

A

Ribosomes are not considered to be organelles; they work as small factories that carry out translation (mRNA → protein).

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40
Q

What are eukaryotic ribosomal subunits?

A

Eukaryotic ribosomal subunits (60S and 40S) assemble in the nucleoplasm and are exported to form the complete ribosome in the cytosol (80S).

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41
Q

What are prokaryotic ribosomal subunits?

A

Prokaryotic ribosomal subunits (50S and 30S) assemble in the cytosol and form complete ribosomes (70S) there.

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42
Q

What do free-floating ribosomes do?

A

Free-floating ribosomes make proteins that function in the cytosol.

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43
Q

What do ribosomes embedded in the rough ER do?

A

Ribosomes embedded in the rough endoplasmic reticulum (rough ER) make proteins that are sent out of the cell or to the cell membrane.

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44
Q

What is the rough endoplasmic reticulum (rough ER)?

A

The rough ER is continuous with the outer membrane of the nuclear envelope and is ‘rough’ because it has ribosomes embedded in it.

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45
Q

What happens to proteins synthesized by ribosomes in the rough ER?

A

Proteins are sent into the lumen of the rough ER for modifications, such as glycosylation.

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46
Q

What are the two possible fates of proteins after modifications in the rough ER?

A

Proteins are either sent out of the cell or become part of the cell membrane.

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47
Q

What characterizes the smooth endoplasmic reticulum (smooth ER)?

A

The smooth ER is an extension of the rough ER, characterized by interconnected flattened sacs without ribosomes.

48
Q

What are the main functions of the smooth ER?

A

The smooth ER synthesizes lipids, produces steroid hormones, and detoxifies cells.

49
Q

What is the function of the Golgi apparatus?

A

The Golgi apparatus stores, modifies, and exports proteins that will be secreted from the cell.

50
Q

What is the structure of the Golgi apparatus?

A

The Golgi apparatus is made up of cisternae, which are flattened sacs.

51
Q

How do vesicles interact with the Golgi apparatus?

A

Vesicles come from the ER and reach the cis face of the Golgi apparatus, then leave from the trans face.

52
Q

What are lysosomes and their function?

A

Lysosomes are membrane-bound organelles in animal cells that contain digestive enzymes to break down cellular waste.

53
Q

What role do lysosomes play in apoptosis?

A

Lysosomes play a role in apoptosis, which is programmed cell death.

54
Q

What are vacuoles and their primary uses?

A

Vacuoles are membrane-bound vesicles used for storage or transport of water, nutrients, and waste.

55
Q

What is the function of central vacuoles in plant cells?

A

Central vacuoles help maintain cell rigidity (turgor) and function similarly to lysosomes.

56
Q

What are contractile vacuoles and where are they found?

A

Contractile vacuoles are found in single-celled organisms and actively pump out excess water.

57
Q

What is the endomembrane system?

A

The endomembrane system is composed of membranes that work together to modify, package, and transport proteins and lipids.

58
Q

Which organelles are included in the endomembrane system?

A

The components include the nucleus, rough and smooth ERs, Golgi apparatus, lysosomes, vacuoles, and cell membrane.

59
Q

What is the role of the Golgi apparatus in the endomembrane system?

A

The Golgi apparatus receives vesicles from the ER, modifies proteins/lipids, and distributes them as secretory products.

60
Q

What do peroxisomes do?

A

Peroxisomes perform hydrolysis, break down stored fatty acids, and help with detoxification.

61
Q

What toxic substance is generated during the processes in peroxisomes?

A

Hydrogen peroxide is generated, which can produce reactive oxygen species (ROS).

62
Q

How do peroxisomes protect cells from hydrogen peroxide?

A

Peroxisomes contain catalase, which breaks down hydrogen peroxide into water and oxygen.

63
Q

What are mitochondria?

A

Mitochondria are the powerhouses of the cell, producing ATP for energy use through cellular respiration.

64
Q

What type of inheritance is associated with mitochondrial DNA?

A

Mitochondrial inheritance is maternal, meaning all mitochondrial DNA in humans originates from the mother.

65
Q

What is the function of chloroplasts?

A

Chloroplasts carry out photosynthesis.

66
Q

What are plastids?

A

Plastids are double-membraned organelles found exclusively within plant cells and algae, that function in photosynthesis and storage of metabolites.

67
Q

What are centrosomes?

A

Centrosomes are organelles found in animal cells containing a pair of centrioles.

68
Q

What is the role of centrosomes during cell division?

A

Centrosomes act as microtubule organizing centers (MTOCs) during cell division.

69
Q

What is the cytoskeleton?

A

The cytoskeleton provides structure and function within the cytoplasm.

70
Q

What are microfilaments?

A

Microfilaments are the smallest structure of the cytoskeleton and are composed of a double helix made of actin filaments.

71
Q

What are the main functions of microfilaments?

A

Microfilaments are involved in cell movement, cleavage furrow formation, cyclosis, and muscle contraction.

72
Q

What are intermediate filaments?

A

Intermediate filaments are between microfilaments and microtubules in size and help with structural support.

73
Q

What is an example of an intermediate filament protein?

A

Keratin is an important intermediate filament protein in skin, hair, and nails.

74
Q

What are microtubules?

A

Microtubules are the largest in size and give structural integrity to cells, made of tubulin protein.

75
Q

What structures do microtubules form?

A

Microtubules form centrioles and are found in cilia and flagella.

76
Q

What is a cleavage furrow?

A

During cell division, myosin motors and actin microfilaments form contractile rings that split the cell.

77
Q

What is cyclosis?

A

The flow (or stirring) of the cytoplasm inside the cell, driven by forces via actin (microfilaments) and myosin movement, similar to muscle contraction.

78
Q

What allows muscle contraction?

A

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

79
Q

What are kinesin and dynein?

A

Motor proteins that transport cargo along microtubules.

80
Q

What are microtubule organizing centers (MTOCs)?

A

Structures present in eukaryotic cells that help organize microtubule extension.

81
Q

What are centrioles?

A

Hollow cylinders made of microtubules.

82
Q

What do centrosomes contain?

A

A pair of centrioles oriented at 90 degree angles to one another.

83
Q

What are cilia?

A

Small hair-like projections made of tubulin found only in eukaryotes.

84
Q

What is the function of cilia?

A

Locomotion of either the cell itself or fluids (e.g., cilia remove debris in the lungs).

85
Q

What are flagella?

A

Longer hair-like structures found in both prokaryotes and eukaryotes.

86
Q

What is the function of flagella?

A

Locomotion of the cell or fluids (e.g., flagella propel sperm).

87
Q

What is the composition of eukaryotic flagella?

A

Composed of polymers of tubulin with a 9+2 array.

88
Q

What is the composition of prokaryotic flagella?

A

Composed of polymers of flagellin and do not have a 9+2 array.

89
Q

How do eukaryotic flagella move?

A

In a bending motion.

90
Q

How do prokaryotic flagella move?

A

In a rotary motion.

91
Q

What is the extracellular matrix (ECM)?

A

Provides extracellular mechanical support for cells.

92
Q

What are the components of the ECM?

A

Proteoglycan, collagen, integrin, fibronectin, laminin.

93
Q

What is proteoglycan?

A

A type of glycoprotein that has a high proportion of carbohydrates.

94
Q

What is collagen?

A

The most common structural protein, secreted by fibroblasts; organized into collagen fibrils.

95
Q

What is integrin?

A

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

96
Q

What is fibronectin?

A

A protein that connects integrin to ECM and helps with signal transduction.

97
Q

What is laminin?

A

Behaves similarly to fibronectin and influences cell differentiation, adhesion, and movement.

98
Q

What are cell walls?

A

Carbohydrate-based structures that provide structural support to cells.

99
Q

What are the components of bacterial cell walls?

A

Primarily made of peptidoglycan, a polysaccharide with peptide chains.

100
Q

What is the composition of archaea cell walls?

A

Made of polysaccharides but does not contain peptidoglycan.

101
Q

What are focal adhesions?

A

Cell-matrix junctions where ECM connects via integrins to actin microfilaments inside the cell.

102
Q

What are hemidesmosomes?

A

Cell-matrix junctions where ECM connects via integrins to intermediate filaments inside the cell.

103
Q

What are tight junctions?

A

Tight junctions form water-tight seals between cells to ensure substances pass through cells.

104
Q

What are desmosomes?

A

Desmosomes provide support against mechanical stress and connect neighboring cells.

105
Q

What are adherens junctions?

A

Adherens junctions are similar in structure and function to desmosomes, connecting neighboring cells via actin microfilaments.

106
Q

What are gap junctions?

A

Gap junctions allow passage of ions and small molecules between cells, formed from transmembrane proteins known as connexons. They are only present in animal cells.

107
Q

What is the middle lamella?

A

The middle lamella is a sticky cement similar in function to tight junctions, found in plant cells.

108
Q

What are plasmodesmata?

A

Plasmodesmata are tunnels with tubes between plant cells that allow cytosol fluids to freely travel between them.

109
Q

What happens to cells in hypotonic solutions?

A

In hypotonic solutions, water enters the cell, causing animal cells to swell and potentially burst (lysis), while plant cells become turgid.

110
Q

What happens to cells in isotonic solutions?

A

Isotonic solutions have the same solute concentration as the cells placed in them.

111
Q

What happens to cells in hypertonic solutions?

A

In hypertonic solutions, water leaves the cell, causing animal cells to shrivel and plant cells to undergo plasmolysis.

112
Q

What are the four basic types of tissues?

A

The four basic types of tissues are epithelial, connective, muscle, and nervous tissues.

113
Q

What are epithelial tissues?

A

Epithelial tissues are cohesive sheets of cells that line internal organs and cover the body.

114
Q

What are connective tissues?

A

Connective tissues support the structure of the organism and include types like cartilage, bone, blood, and adipose (fat).

115
Q

What is muscle tissue responsible for?

A

Muscle tissue is responsible for body movement and is subdivided into smooth, skeletal, and cardiac muscles.

116
Q

What is nervous tissue composed of?

A

Nervous tissue is composed of neurons to send information and various support cells called glial cells.

Biology DAT (3 decks)

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