Cell Biology

Question 1

State three parts of the cell theory

Answer 1

1. Living organisms are composed of cells
2. Cells are the smallest units of life
3. Cells come from pre-existing cells

Question 2

Outline evidence that supports the cell theory

Answer 2

1. Subcellular components have never been seen to perform the functions of life
2. Biologists examined tissues from both plants and animals, and saw that every specimen contained at least one or more cell
3. We have observed cells coming from other cells, but never observed spontaneous generation

Question 3

Compare the use of the word theory in daily language and scientific language.

Answer 3

Daily language: a theory is a guess where there is doubt

Scientific language: a theory is something that has been shown to be true through repeated observations and experiments

Question 4

Outline the functional characteristics of life

Answer 4

Metabolism - organisms carry out chemical reactions such as the synthesis of ATP during cellular respiration

Response - organisms respond and adapt to external stimuli

Growth - organisms increase in size until the cell is too large to function efficiently

Homeostasis - organisms maintain a stable environment within the cell

Reproduction - organisms are able to reproduce (prokaryotes: binary fission, eukaryotes: asexually or sexually)

Nutrition - organisms create or synthesize their own or consumes organic molecules

Excretion - organisms remove waste products

Question 5

Outline the activities occurring in the volume and at the surface of the cell

Answer 5

Volume: many metabolic reactions which require gases and chemical nutrients and produce waste

Surface area: regulates transport of molecules in and out of the cell

Question 6

Calculate the surface area, volume, and SA:V ratio of a cell

Answer 6

SA: length * width

Volume: length * width * height

SA:V ratio: SA / volume

Question 7

Explain the benefits and limitations of using cubes to model the surface area and volume of a cell

Answer 7

Benefits: cubes can be manipulated, visualized, and easily measured

Limitation: most cells are not cubic in shape

Question 8

Describe the relationship between cell size and the SA:V ratio of the cell

Answer 8

As the cell grows bigger, its volume increases and the cell membrane surface expands. However, the volume increases faster than the SA. Therefore, the amount of surface area relative to the volume (SA:V) decreases.

Question 9

Explain why cells are often limited in size by the SA:V ratio

Answer 9

Smaller volume requires fewer metabolic nutrients and waste to be transported through the cell membrane.

Relatively more cell membrane for transporting materials into/out of the cell.

Molecules have shorter distance to diffuse within the cell.

Question 10

List three adaptations of cells that maximize the SA:V ratio

Answer 10

Branching

Microvilli

Folded membranes

Question 11

Define and provide an example of a multicellular organism

Answer 11

An organism that consists of more than one cell. An example is Homo sapien.

Question 12

Define and provide an example of a unicellular organism

Answer 12

An organism that consists of only one cell. An example is paramecium.

Question 13

Define “emergent property”

Answer 13

Properties that arise from the interaction of cellular components.

Question 14

Provide and example of emergent properties at different hierarchical levels of life

Answer 14

1) Cells grouped together to form tissues
2) Organs are then formed from the functional grouping of multiple tissues
3) Organs that interact may form organ systems capable of carrying out specific body functions
4) Organs systems collectively carry out the life functions of the complete organism

Question 15

Define “tissue”

Answer 15

A group or collection of similar cells that work together to perform a specific function within an organism

Question 16

Outline the benefits of cell specialization in a multicellular organism

Answer 16

1) Efficiency in function - specialized cells are more efficient at performing specific tasks compared to generalized cells. For example, red blood cells are specialized for oxygen transport, possessing a unique shape and lacking a nucleus to maximize their capacity for oxygen binding and circulation.
2) Division of labor - cell specialization allows for the division of labor within an organism. This division enables multicellular organisms to perform complex functions more efficiently than single-celled organisms.
3) Formation of tissues and organs - specialized cells organize into tissues with specific functions. In turn, tissues assemble into organs that work together to carry out essential physiological processes.

Question 17

Define “differentiation”

Answer 17

The process during development whereby newly formed cells become more specialized and distinct from one another as they mature

Question 18

Describe the relationship between cell differentiation and gene expression

Answer 18

During differentiation, a cell only uses the genes that it needs to follow its pathway of development. Other genes are unused (turned off)

Question 19

Define “zygote”

Answer 19

The fetus at its earliest stage of development following fertilization, characterized as a diploid cell formed by the fusion of two haploid gametes during fertilization

Question 20

Define “embryo”

Answer 20

A development of the zygote after it has underwent multiple divisions

Question 21

List 2 key properties of stem cells that have made them on the active areas of research in biology and medicine today

Answer 21

• Unspecialized, which allows scientists to differentiate into any bodily cell (treatment of disease)
• Divides indefinitely

Question 22

Explain why stem cells are most prevalent in the early embryonic development of a multicellular organism

Answer 22

During early embryonic development, stem cells possess pluripotency, meaning they have the ability to differentiate into many different cell types. They are mostly prominent in the early development of multicellular organisms, as the fetuses require great numbers of tissues to form necessary organs for survival

Question 23

Contrast the characteristics of embryonic, umbilical cord, and adult somatic stem cells

Answer 23

Embryonic:
- Derives from the inner cell mass of the blastocyst
- Pluripotent: potential to differentiate into any cell type in the body

Umbilical cord:
- Derives from the blood or tissue of the umbilical word following childbirth
- Multipotent: more limited potential to differentiate

Adult somatic:
- Derives from various tissues and organs of the adult organism
- Multipotent: even further limited potential to differentiate

Question 24

Define “totipotent”, “multipotent”, and “pluripotent”

Answer 24

Totipotent: can differentiate into any type of cell and can give rise to a complete organism

Pluripotent: can differentiate into all body cells, but cannot give rise to a whole organism

Multipotent: can differentiate into a few closely related types of body cells

Question 25

Describe features of striated muscle fibers that make them a discrepancy from an atypical cell

Answer 25

- Muscle cells fuse to form fibres that may be very long (>300mm) - Multiple nuclei despite being surrounded by a single, continuous plasma membrane

Question 26

Describe features of aseptate fungal hyphae that make them a discrepancy from an atypical cell

Answer 26

- No dividing cell walls (septa), which results in a shared cytoplasm and multiple nuclei

Question 27

Describe features of giant algae that make them a discrepancy from an atypical cell

Answer 27

- A single cell can grow to be 100mm

Question 28

Describe characteristics of Paramecium that enable it to perform functions of life

Answer 28

- Surrounded by small hairs called cilia which allow it to move (responsiveness) . Engulf food via a specialized membranous feeding grove called a cytosome (nutrition) - Food particles are enclosed within small vacuoles that contain enzymes for digestion (metabolism) - Solid wastes are removed via an anal pore, while liquid wastes are pumped out via contractile vacuoles (excretion) - Essential gases enter and exit the cell via diffusion (homeostasis) - Divide asexually via fission, although horizontal gene transfer car occur via conjunction (reproduction)

Question 29

Describe characteristics of Scenedesmus that enable it to perform the functions of life

Answer 29

- Gases and other essential materials are exchanged via diffusion (nutrition / excretion) - Chlorophyll pigments allow organic molecules to be produced via photosynthesis (metabolism) - Daughter cells form as non-motile autospores via the internal asexual division of the parent cell (reproduction) - May exist as unicells or form colonies for protection (responsiveness)

Question 30

Outline why stem cells are used in medical research and treatment

Answer 30

Stem cells can differentiate into all cells, meaning that they can be used to treat damaged tissue in medical treatment.

Question 31

Outline the cause and symptoms of Stargardt's disease

Answer 31

Cause: Gene mutation on gene ABCA4 in fetus Symptoms: Photoreceptor cells degenerate which leads to a progressive loss of central vision

Question 32

Explain how stem cells are used in the treatment of Stargardt's diease

Answer 32

Patients are given retinal cells derived from human embryonic stem cells, which are injected into the retina. These cells then divide, providing the patient with healthy retina cells.

Question 33

Outline the cause of leukemia

Answer 33

High levels of abnormal white blood cells which lead to a type of cancer in the blood or bone marrow

Question 34

Explain how stem cells are used in the treatment of leukemia

Answer 34

Hematopoietic stem cells (HSCs) are multipotent stem cells which are harvested from bone marrow, peripheral blood or umbilical cord blood. This may derive from the patient or a suitable donor. Then, the patient undergoes chemotherapy to get rid of the diseased blood cells. Lastly, the HSCs are transplanted back into the bone marrow where they differentiate to form new healthy white blood cells.

Question 35

Discuss the benefits and drawbacks in using adult stem cells; embryonic stem cells; cord blood stem cells

Answer 35

Benefits - Adult: Effective for certain conditions - Embryonic: Greatest yield of stem cells - Umbilical cord: Effective for multiple conditions Drawbacks - Adult: Limited in its scope of application - Embryonic: Destruction of potential living organisms - Umbilical cord: Availability and access - storing them are costly

Question 36

Define "magnificaiton"

Answer 36

The act of enlarging something

Question 37

State why the magnification of a drawing or micrograph is not the same as the magnification of the microscope

Answer 37

A microscope will always be to scale.

Question 38

Use a formula to calculate the magnification of a micrograph or drawing

Answer 38

M = I / A I = M * A A = M / I

Question 39

Define "trend" and explain why trends are useful in scientific study

Answer 39

Can predict how something will be over a period of time.

Question 40

Outline the major differences between prokaryotic and eukaryotic cells

Answer 40

Prokaryotic: - Cell wall - Naked DNA - Flagellum Eukaryotic: - No cell wall - DNA contained within nucleus -No flagellum

Question 41

List the functions of the following structures of a prokaryotic cell: cell membrane, nucleoid, plasmid, cytoplasm, ribosome, cell wall, pili, capsule, and flagella

Answer 41

Cell membrane: Nucleoid: Plasmid: Cytoplasm: Ribosome: Cell wall: Pili: Capsule: Flagella:

Question 42

Contrast the size of eukaryotic and prokaryotic ribosomes

Answer 42

Eukaryotic: Prokaryotic:

Question 42

State the meaning and advantages of eukaryotic cells being "compartmentalized"

Answer 42

Enzymes and substrates used in a process can be concentrated in a small area.

Question 43

State structural differences between plant and animal cells

Answer 43

Animal cells have only a plasma membrane, whereas plant cells have an additional membrane: the cell wall.

Question 44

Define "asexual reproduction"

Answer 44

An organism's ability to reproduce by itself.

Question 45

Outline the steps of binary fission

Answer 45

Binary fission is how prokaryotes reproduce asexually. It means splitting in two. The bacterial chromosome is replicated so there are two identical copies. These are moved to opposite sides of the organism, and the wall and plasma membrane are pulled inwards so the cell pinches apart to create two identical cells.

Question 46

Define "resolution"

Answer 46

The ability of the microscope to show two close objects separately in the image.

Question 47

Compare the functionality of light and electron microscopes

Answer 47

Light microscope: - Resolution: 0.25μm - Magnification: x 500 Electron microscope: - Resolution: 0.25nm - Magnification: x 500,000

Question 48

State the function of an exocrine gland cell

Answer 48

To secrete fluids on the exterior of the body (sweat glands, mammary glands).

Question 49

Describe the following function of the following structures in an exocrine gland cell: plasma membrane, nucleus, mitochondria, Golgi apparatus, lysosomes, vesicles, and endoplasmic reticulum

Answer 49

Plasma membrane: Nucleus: Mitochondria: Golgi apparatus: Lysosomes: Vesicles: Endoplasmic reticulum:

Question 50

State the function of a palisade mesophyll cell

Question 51

Draw a labeled diagram of a palisade cell from the leaf mesophyll

Question 52

Describe the function of the following structures in a palisade mesophyll cell: cell wall, plasma membrane, chloroplasts, vacuole, nucleus, and mitochondria

Answer 52

Cell wall: supports and protects the cell Plasma membrane: controls entry and exit of substances Chloroplasts: carries out photosynthesis Vacuole: transport molecules Nuclear membrane: protects chromosomes Mitochondria: synthesizes ATP

Question 53

Explain why the ultrastructure of prokaryotic cells must be based on electron micrographs

Answer 53

They are too small to be seen well enough with a light microscope.

Question 54

Draw the ultrastructure of E. coli as seen on an electron micrograph

Question 55

Draw and label a diagram the ultrastructure of a generic animal cell

Question 56

Draw and label a diagram of the ultrastructure of a generic plant cell

Question 57

Explain why cells with different functions will have different structures

Answer 57

Different structures are specialized for cell functions. Muscle cells will for example have more mitochondria, as these synthesize large amounts of ATP.

Question 58

Identify ultrastructures visible in a micrograph of a eukaryotic cell

Answer 58

Look for rER, mitochondrion, golgi apparatus, nucleus

Question 59

Given a micrograph of a cell, deduce the function of the cell based on the structure present,

Question 60

With reference to a specific example, explain how an improvement in apparatus allowed for greater understanding of cell structure

Answer 60

The structure of membranes: - First, Davson and Danielli proposed that the membrane of cells are composed of phospholipids and proteins in a sandwich-like structure. This was during the 1930s, and in the 1950s, the first high magnification electron micrographs were produced. This led to the Singer-Nicolson model, which proposed that the membrane was more fluid then the first model proposed.

Question 61

Draw a simplified diagram of the structure of the phospholipid, including a phosphate-glycerol head and two fatty acid tails

Question 62

Define "hydrophilic" and "hydrophobic"

Answer 62

Hydrophilic: water attracting Hydrophobic: water repelling

Question 63

Define "amphipathic" and outline the amphipathic properties of phospholipids

Answer 63

Having both hydrophobic and hydrophilic properties. A phospholipid has a hydrophilic head and hydrophilic tails.

Question 64

Explain why phospholipids form bilayers in water, with reference to hydrophilic heads and two hydrophobic hydrocarbon tails

Answer 64

Phospholipids form bilayers in water to protect the water-hating tails. The hydrophilic heads are facing outwards, whilst the hydrophobic tails face inwards.

Question 65

State the primary function of the cell membrane

Question 66

Contrast the structure of integral and peripheral proteins

Answer 66

Integral proteins: - Embedded into the phospholipid bilayer. Peripheral proteins: - Attached to an outer surface of the membrane.

Question 67

List at least four functions (with examples) of membrane bound proteins

Question 68

Contrast the two types of transport proteins: pumps and channels

Answer 68

Pumps: active transport Channels: facilitated diffusion / passive transport

Question 69

Identify the structure of cholesterol in molecular diagrams

Question 70

Describe the structural placement of cholesterol within the cell membrane

Question 71

Outline how temperature affects cell membrane fluidity

Question 72

Describe the function of cholesterol molecules in the cell membrane

Question 73

Draw and label the structure of membranes. Include: phospholipid bilayer, integral proteins spanning the membrane, peripheral proteins on membrane surface, protein channels with a pore, glycoproteins with a carbohydrate side chain, cholesterol between phospholipids in the hydrophobic region

Question 74

Describe the observations and conclusions drawn by Davson and Danielli in discovering the structure of cell membranes

Question 75

Describe conclusions about cell membrane structure drawn from freeze-etched electron micrograph images of the cell membrane

Question 76

Describe conclusions about cell membrane structure drawn from cell fusion experiments

Question 77

Compare the Davson-Danielli model of membrane structure with the Singer-Nicolson model

Question 78

Explain what models are and their purposes in science

Question 79

Explain why models have limitations

Question 80

Summarize why scientific models change over time

Question 81

Describe why the understanding of cell membrane structure has changed over time

Question 82

Describe "simple diffusion"

Question 83

Explain two examples of simple diffusion of molecules into and out of cells

Question 84

Outline factors that regulate the rate of diffusion

Question 85

Describe "facilitated diffusion"

Question 86

Describe one example of facilitated diffusion through a protein channel

Question 87

Define "osmosis"

Question 88

Predict the direction of water movement based upon differences in solute concentration

Question 89

Compare active transport and passive transport

Question 90

Explain one example of active transport of molecules into and out of cells through protein pumps

Question 91

Describe the fluid properties of the cell membrane and vesicles

Question 92

Explain vesicle formation via endocytosis

Question 93

Outline two examples of materials brought into the cell via endocytosis

Question 94

Explain release of materials from cells via exocytosis

Question 95

Outline two examples of materials released from a cell via exocytosis

Question 96

List two reasons for vesicle movement

Question 97

Outline how phospholipids and membrane bound proteins and synthesized and transported to the cell membrane

Question 98

Describe how organelles of the endomembrane system function together to produce and secrete proteins (rough ER, smooth ER, Golgi apparatus, vesicles)

Question 99

Describe the structure of the sodium-potassium pump

Question 100

Describe the role of the sodium-potassium pump in maintaining neuronal resting potential

Question 101

Outline the six steps of sodium-potassium pump action

Question 102

Describe the structure of the potassium channel

Question 103

Describe the mechanism of potassium movement through the potassium channel

Question 104

Explain the specificity of the potassium channel

Question 105

Describe the action of the "voltage gate" of the potassium channel

Question 106

Explain what happens to cells when placed in solutions of the same osmolarity, higher osmolarity, and lower osmolarity

Question 107

Outline the use of normal saline in medical procedures

Question 108

Define "osmolarity", "isotonic", "hypotonic", and "hypertonic"

Question 109

Calculate the percentage change between measurement values

Question 110

Determine osmolarity of a sample given changes in mass when placed in solutions of various tonicities

Question 111

Define "quantitative" and "qualitative"

Question 112

Determine measurement uncertainty of a measurement tool

Question 113

Explain the need for repeated measurements in experimental design

Question 114

Explain the need to control variables in experimental design

Question 115

Discuss implications of all cells formed from preexisting cells

Question 116

Outline the four processes needed for the spontaneous origin of cells on Earth

Question 117

Outline the experiments of Miller and Urey into the origin of organic compounds

Question 118

Define "polymerization", "monomer", and "polymer"

Question 119

Outline two properties of RNA that would have allowed it to play a role in the origin of life

Question 120

State the endosymbiosis theory

Question 120

Outline why fatty acids were likely the primary component of the membrane of early cells

Question 121

Outline the major events in the origin of eukaryotic cells

Question 122

Describe the evidence for the endosymbiotic theory

Question 123

Define "spontaneous generation"

Question 124

Describe Pasterur's experiments about spontaneous generation

Question 125

Explain why Pasteur's experiments did not support the idea of spontaneous generation

Question 126

Outline historical thinking about spontaneous generation

Question 127

Summarize the Redi experiment

Question 128

Summarize the Spallanzani experiment

Question 129

List reasons why biologists now universally accept that cells only come from preexisting cells

Question 130

State the function of mitosis

Question 131

List processes which involve mitosis

Question 132

State the names of the four phases of mitosis

Answer 132

PROPHASE: - Chromosomes condense - The two centrosomes move towards opposite poles - Spindle fibres emerge from the centrosomes - Nuclear envelope breaks down - Nucleolus disappears METAPHASE: - Centrosomes reach opposite poles - Spindle fibres continue extending from centrosomes - Chromosomes line up at equator - Spindle fibres reach the chromosomes and attach to the centromeres (each sister chromatid is attached to a spindle fibre originating from opposite poles ANAPHASE: - Sister chromatids separate at the centromere - Spindle fibres begin to shorten - Separated sister chromatids (now called chromosomes) are pulled to opposite poles. - Cell begins to divide TELOPHASE: - Chromosomes arrive at opposite poles and begin to decondense - Nuclear envelopes begin to reform around chromosomes - Spindle fibres break down - New nucleoli form within each nucleus

Question 133

Draw typical eukaryotic cells as they would appear during the four phases of mitosis

Question 134

Outline four events that occur during prophase

Question 135

Outline the process of metaphase

Question 136

Outline the process of anaphase

Question 137

Outline four events that occur during telophase

Question 138

Describe the structure of a replicated chromosome, include the centromere and sister chromatids

Question 139

Explain why chromosomes must condense during mitosis

Question 140

Define "cytokineses"

Question 141

State the difference between mitosis and cytokinesis

Question 142

Contrast cytokinesis in plant and animal cells

Question 143

Describe the formation of the cleavage furrow in animal cell cytokineses

Question 144

Describe the formation of the middle lamella and cell wall in plant cell cytokinesis

Question 145

List examples of metabolic reactions occurring during cell interphase

Question 146

Outline events og G1, S, G2, and G0 phases

Question 147

Explain the role of cyclin and cyclin-CDK complexes in controlling the cell cycle

Question 148

State the role of cyclins D, B, A, and E in the cell cycle

Question 149

Define "tumor", "benign", "malignant", "metastasis", "cancer", "mutagen", and "carcinogen"

Answer 149

Tumor: Benign: Malignant: Metastasis: Cancer: Mutagen: Carcinogen:

Question 150

Describe why mutagens are not necessarily carcinogens

Question 151

Describe how cancer arises, referring to accumulation of mutations over time

Question 152

Explain the relationship between oncogenes, tumor suppressor genes, and cancer

Question 153

Explain the use of correlations to determine the relationship between two variables

Question 154

Explain why the existence of a correlation does not necessitate a causal relationship between the two variables

Question 155

Calculate a correlation coefficient using Pearson's R

Question 156

Determine if a correlation coefficient value is significant

Question 157

Define significant as related to the relationship between two variables

Question 158

Use of epidemiological case study information to outline the relationships between smoking and cancer

Question 159

Determine the phase of mitosis of a cell viewed in a micrograph or with a microscope

Question 160

State the formula for calculation of a mitotic index

Question 161

Calculate the mitotic index of a tissue as seen in a micrograph

Question 162

Outline the use of mitotic index calculations in diagnosis and treatment of cancer

Question 163

Outline the discovery of cycling including the role of serendipity