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MCAT Biology > 1: The Cell > Flashcards

1: The Cell Flashcards

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1
Q

What are the four basic tenets of cell theory?

A

1) All living things are composed of cells
2) Cell is the basic functional unit of life
3) Cells arise only from pre-existing cells
4) Cells pass on genetic information in form of nucleic acids

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2
Q

Name the eukaroytic organelles

A

Nucleus, nucleolus, mitochondria, lysosomes, endoplasmic reticulum, golgi apparatus, peroxisomes

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3
Q

What is a peroxisome?

A
  • Contain hydrogen peroxide.
  • Break down very long chain fatty acids through beta-oxidation.
  • Also participate in phospholipid synthesis and the pentose phosphate pathway
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4
Q

What are the functions of the cytoskeleton?

A
  • Provides stability and rigidity to cell structure

- provides transport pathways within cell

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5
Q

What are the three components of the cytoskeleton?

A

Microfilaments
Microtubules
Intermediate filaments

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6
Q

What are cytoskeletal microfilaments?

A
  • solid polymerized rods of actin

- organized into bundles/networks

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7
Q

What are the functions of cytoskeletal microfilaments?

A
  • PROTECTION: resistant to compression and fracture => protect cell
  • MOVEMENT: use ATP to generate force through interaction with myosin => muscle contraction
  • REPRODUCTION: during cytokinesis, ring of microfilaments at site of division form cleavage furrow. As actin filaments contract, cell divides.
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8
Q

What are microtubules? What is their function?

A
  • Hollow polymers of tubular proteins

- Radiate through cell, providing pathways for motor proteins (kinesin, dynein) to carry vesicles

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9
Q

Discuss some specialized microtubules and their functions

A

CILIA, FLAGELLA - both microtubule projections

In eukaryotes, both have 9-2 structure [FINISH THIS]

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10
Q

What are centrioles?

A
  • Found in the cell region called centrosome.
  • Organizing center for microtubules
  • Structured as nine triplets of microtubules with hollow center
  • Migrate to opposite poles of dividing cell during mitosis. Microtubules emanating from centrioles attach to chromosomes via kinetochores
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11
Q

What are intermediate filaments?

A

Group of filamentous proteins: keratin, desmin, vimentin, lamins

Functions: cell-cell adhesion, cytoskeleton integrity, cell rigidity, anchoring organelles

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12
Q

What are the four animal tissue types?

A

Nervous, muscle, epithelial, connective

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13
Q

Describe epithelial cells

A
  • Covers body; lines cavities
  • Protects against invasion, desiccation
  • cells tightly joined to each other and underlying connective tissue with a basement membrane
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14
Q

What is the parenchyma of an organ?

A

The functional parts!

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15
Q

What are some examples of epithelial cells serving as the parenchyma of an organ?

A
  • Nephrons of kidney
  • Hepatocytes of liver
  • Acid-producing cells of stomach
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16
Q

What are the different classes of epithelial cell?

A
  • Simple epitheila - one layer
  • Stratified epithelia - multiple layers
  • Pseudostratified epithelia - appear to have multiple layers but really just difference in cell height.
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17
Q

What are the different shapes of epithelial cell?

A

Cuboidal, columnar, squamous (flat, scale-like)

18
Q

What is a stroma?

A

Support structure

19
Q

What are examples of connective tissues?

A

Bone, cartilage, tendons, adipose tissue, blood

20
Q

What produces the extracellular matrix?

A

Produced by collagen/elastin secreted by connective cells

21
Q

In what region of a prokaryote is DNA found?

A

The nucleoid region

22
Q

How are archaea similar to bacteria and eukaryotes?

A

To eukaryotes: start translation with methionine, similar RNA polymerases, histones

To bacteria: single circular chromosome, division by binary fission/budding

23
Q

What are the main shapes of bacteria?

A

Cocci - spherical
Bacilli - rod
Spirilli - spiral

24
Q

What are the four aerobic metabolic bacterial categories?

A

Obligate aerobes
Obligate anaerobes
Facultative aerobes
Aerotolerant anaerobes

25
Q

What is the bacterial envelope made from?

A

Cell wall - outer barrier
Cell membrane , composed of phospholipids
(Cell wall and cell membrane together known as envelope)

26
Q

Discuss differences in gram positive/gram negative bacterial cell walls

A

Gram positive - thick layer of peptidoglycan; also lipoteichoic acid (causes immune inflammatory response)

Gram negative - v thin layer of peptidoglycan, separated from membrane by periplasmic space. Outer membrane contains phospholipids and lipopolysaccharide (causes much stronger immune inflammatory response)

27
Q

Discuss the structure of bacterial flagella

A

Filament - long, hollow, helical structure made of flagellin
Basal body - anchors flagellum to cell, motor, rotates up to 300hz!
Hook - connects the two

28
Q

Discuss the differences between prokaryotic and eukaryotic ribosomes

A 
Prokaryotic = 30S
Eurkaryotic = 40S and 60S
29
Q

Do prokaryotes have a cytoskeleton?

A

Yes, but it’s much less complex than eukaryotic cytoskeletons!

30
Q

What do we call a plasmid that can integrate into the bacterial genome?

A

An episome

31
Q

What are transposons?

A

Genetic elements that insert or remove themselves from the genome

32
Q

What are the phases of bacterial growth?

A

Lag phase - bacteria adapt to local conditions
Log phase (exponential phase) - rapid growth
Stationary phase
Death phase

33
Q

What is a virus protein coat called?

A

Capsid, made of capsomeres

34
Q

What is a virion?

A

An individual virus particle

35
Q

What is the function of the tail sheath and tail fibers of a bacteriophage?

A

Sheath - injects nucleic acids

fibers - attaches/recognizes bacteria

36
Q

What are positive sense and negative sense ssRNA viruses?

A

Positive sense - ssRNA can directly be translated by host cell
Negative sense - complementary RNA strand must first be synthesized by RNA replicase

37
Q

What is a retrovirus?

A

ssRNA virus, to which complementary DNA is made using reverse transcriptase. DNA then integrated into genome

38
Q

Name three ways a virion can leave a cell

A
  • Virus initiates cell death
  • Cell lyses from large number of virions
  • Virion extrudes from cell, keeping host cell alive
39
Q

What is a provirus?

A

Same as a prophage - virus integrated into host genome during lytic cycle

40
Q

Why may a bacterium tolerate a phage?

A
  • Infection with one phage = less likely infection with other
  • Some phages are innocuous
41
Q

What is a prion? How do they cause disease?

A
  • Infectious protein
  • May trigger misfolding of nearby proteins – reducing solubility and ability of cell to remove protein
  • Aggregates reduce cell function
    Examples: mad cow, familial fatal insomnia
42
Q

What is a viroid?

A
  • Very short ssRNA, usually infects plants
  • Bind to many RNA sequences, silence genes in plant genome
  • Human examples: Hep D

MCAT Biology (5 decks)

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