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Biology of Cells > Basics > Flashcards

Basics Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Which cells have membrane bound organelles?

A

Eukaryotes.

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2
Q

Which cells have a nucleus?

A

Eukaryotes.

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3
Q

Which cells have no proteins (histones) associated with their DNA?

A

Prokaryotes.

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4
Q

What size are the ribosomes in prokaryotes?

A

70S

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5
Q

What size are the ribosomes in eukaryotes?

A

80S

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6
Q

What groups are the prokaryotes divided into?

A

Bacteria and Archaea.

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7
Q

Which cells possess ribosomes?

A

Both prokaryotes and eukaryotes.

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8
Q

What is the function of a ribosome?

A

Carry out translation in protein synthesis.

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9
Q

What are the three main components of a ribosome?

A

Large protein subunit, small protein subunit and ribosomal RNA (rRNA).

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10
Q

What is the distinction between cytoplasm and cytosol?

A

Cytoplasm is the aqueous content of the cell, excluding the nucleus. Cytosol is the soluble component of the cytoplasm.

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11
Q

What is the function of the plasma membrane?

A

To surround cell contents and control entry and exit of materials into and out of cell.

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12
Q

What are the main components of the plasma membrane?

A

Lipids and proteins.

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13
Q

Where is the nucleolus found, and what is its function?

A

The nucleolus is found in the nucleus, and its function is to synthesise the components of ribosomes.

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14
Q

Which cells are mitochondria found in?

A

Eukaryotes.

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15
Q

What is the function of mitochondria?

A

To perform aerobic respiration.

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16
Q

Which cells are chloroplasts found in?

A

Eukaryotes (plant and algal cells).

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17
Q

What is the function of chloroplasts?

A

To perform photosynthesis.

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18
Q

What is an unusual feature shared by mitochondria and chloroplasts?

A

They both contain their own DNA and 70S ribosomes.

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19
Q

What are the features and functions of the rough endoplasmic reticulum?

A

It has ribosomes on its surface.
Large surface area for synthesis of proteins and glycoproteins.
Acts as a pathway for the transport of materials, especially proteins, through the cell.

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20
Q

What is the function of the smooth endoplasmic reticulum?

A

Synthesis, storage and transport of lipids and carbohydrates.

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21
Q

What is the function of the Golgi apparatus?

A

Sorts, stores and modifies proteins and lipids from the ER for excretion.

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22
Q

Describe the lysosome and its function.

A

Lysosome is a vesicle at low pH, full of hydrolytic enzymes to degrade materials such as redundant organelles and macromolecules.

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23
Q

Describe the structure and function of the vacuole.

A

It is a large fluid-filled compartment surrounded by the tonoplast membrane, held at low pH. It can have diverse functions in different cells, including digestion, storage and maintenance of turgor pressure.

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24
Q

What are endosomes?

A

Membrane-bound vesicles created by invagination of the plasma membrane.

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25
Q

Which cells have cell walls?

A

Plants, algae and fungi (eukaryotes), and prokaryotes.

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26
Q

What are peroxisomes?

A

Small, vesicular compartments in which oxidative reactions take place (such as the breakdown of fatty acids).

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27
Q

What is the meaning of ‘amphiphilic’ with respect to lipids?

A

They have a hydrophobic end and a hydrophilic end.

28
Q

What are the implications of the amphiphilic nature of membrane lipids?

A

They spontaneously self-associate to form a vesicle with a bilayer.

29
Q

Why is the ‘fluid mosaic model’ used for plasma membranes?

A

Plasma membranes have a dynamic, ‘fluid’ structure, and are like a mosaic in that they are formed of a lipid bilayer with proteins and other macromolecules embedded in them.

30
Q

Macromolecules in the cell membrane can diffuse freely through it, unless…

A

They are tethered to other cellular structures.

31
Q

Plasma membranes are selectively permeable, what does this mean?

A

Only small, non-polar, lipid soluble molecules can diffuse through the lipid bilayer. Other materials require proteins.

32
Q

What are bacterial cell walls made of?

A

Peptidoglycan.

33
Q

What is the difference between gram-positive and gram-negative bacteria?

A

Gram positive bacteria have a cell wall outside a plasma membrane (so it can be stained by the violet dye used in Gram staining). Gram-negative bacteria have a thinner cell wall between two plasma membranes.

34
Q

Describe the composition of plant cell walls.

A

Tensile polysaccharide fibres, cross-linked by hydrogen bonds and embedded in a pectin matrix.

35
Q

What is pectin?

A

A highly hydrated matrix of different polysaccharides.

36
Q

What are the tensile fibres in the cell walls of higher plants?

A

Cellulose.

37
Q

What are the key roles of the cytoskeleton?

A

Source of shape and movement of cells, and provides tracks for molecular motors to move organelles and vesicles around the cell.

38
Q

Give two examples of ‘molecular motors’.

A

Kinesin and dynein.

39
Q

Name the three types of filament in the cytoskeleton.

A

Microtubules.
Actin filaments.
Intermediate filaments.

40
Q

What is the role of microtubules?

A

Determine the position of organelles and direct intracellular transport.

41
Q

What is the role of actin filaments?

A

They determine many aspects of cell shape, particularly at the cell surface, and are important in whole-cell movement.

42
Q

What is the role of intermediate filaments?

A

Provide mechanical strength.

43
Q

What are the components of actin filaments?

A

Actin subunits.

44
Q

What are the components of microtubules?

A

α-tubulin and β-tubulin subunits.

45
Q

What are filaments made up of?

A

Small, soluble, protein subunits.

46
Q

Why is rapid assembly and disassembly of cytoskeletal filaments possible?

A

Subunits are held together by weak, non-covalent interactions.

47
Q

What are motor proteins, and how do they generate mechanical force? Give an example.

A

They are ‘molecular machines’ that convert hydrolysis of ATP into mechanical force. An example is myosin in muscle cells.

48
Q

What are the components of eukaryotic cilia and flagella?

A

Microtubules and dynein.

49
Q

What are prokaryotic flagella made out of?

A

A protein called flagellin.

50
Q

What part of ribosome synthesis takes place in the nucleolus, and what part takes place in the cytoplasm?

A

rRNA is synthesised and added to protein subunits in the nucleolus. The subunits are then exported into the cytoplasm and assembled into a ribosome there.

51
Q

What is the function of the smaller ribosomal subunit?

A

Provides a framework for protein assembly.

52
Q

What is the function of the larger ribosomal subunit?

A

Provides catalytic activity to form peptide bonds between amino acids.

53
Q

What is the catalyst in a ribosome?

A

A ribozyme (a catalytic RNA molecule).

54
Q

Where are transmembrane proteins and proteins destined for secretion produced?

A

Ribosomes on the RER.

55
Q

Where are non-transmembrane and non-secreted proteins synthesised?

A

Free ribosomes in the cytoplasm.

56
Q

Define endocytosis.

A

The movement of materials out of the plasma membrane or external environment into the cell.

57
Q

Define endocytosis.

A

The movement of materials out of the plasma membrane or external environment into the cell.

58
Q

Define exocytosis.

A

The movement of materials into the plasma membrane or into the external environment, out of the cell.

59
Q

Name the types of junctions that can form between cells.

A

Anchoring/adhesive junctions.

Channel-forming junctions.

60
Q

What is an anchoring junction?

A

Transmembrane junctional protein links the cytoskeleton either to extracellular material secreted by both cells, or to a partner protein in the other cell.

61
Q

What are channel-forming proteins?

A

Formed by complexes of connexin proteins.

62
Q

What can be exchanged through channel-forming proteins?

A

Ions and small water-soluble molecules.

63
Q

True or false?

Cells can interact at a distance, without junctions.

A

True - they can do so through chemical signals like hormones.

64
Q

Two words describing development, implying that cellular communication is required.

A

Spatial and temporal.

65
Q

Describe transcription.

A

Transcription factors bind to a specific promoter region, causing DNA to unzip, and forming a complex with RNA polymerase.
Free RNA nucleotides line up with complementary bases on DNA, and are joined with phosphodiester bonds, catalysed by RNA polymerase.
This forms pre-mRNA.
pre-mRNA is spliced to remove introns, forming mRNA.
mRNA diffuses out of nucleus through nuclear pores.

66
Q

Describe translation.

A

mRNA binds to ribosome.
Ribosome reads mRNA bases one codon at a time.
tRNA with complementary anti-codon and corresponding amino acid binds to the ribosome, which then reads next codon and another tRNA binds.
Two amino acids then joined by a peptide bond (amide linkage), catalysed by catalytic rRNA in the ribosomal structure.
A third codon is read and a third complementary tRNA binds, at which point the first tRNA is released, as only two tRNA molecules can be bound at once.
The process continues until a ‘stop’ codon is reached.
mRNA, ribosome and new polypeptide released.

Biology of Cells (7 decks)

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