Cells Flashcards

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1
Q

Explain the fluid mosaic model

A
  • Cell membrane is fluid in that phospholipids and proteins are not stationary but can move rapidly across surface of membrane
  • Cell membrane is a mosaic in that many different protein molecules are randomly scattered and embedded throughout phospholipid bilayer
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2
Q

What can pass through the phospholipid bilayer

A
  • Small hydrophobic molecules
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2
Q

Describe structures and functions of cell membrane

A
  • Partially permeable
  • Protects cell from surrounding environment
  • Controls movement of substances in/out of cell
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3
Q

What does cytoplasm contain

A
  • Cytosol
  • Cytoskeleton
  • Organelles
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3
Q

What is cytosol

A
  • Aqueous solution of essential ions, soluble proteins and soluble organic compounds like sugars and amino acids
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3
Q

What is cytoskeleton

A
  • Network of protein fibres that give support, motility and regulation to cell
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4
Q

Describe structures and functions of nucleus

A
  • Largest organelle in cell
  • Spherical
  • Consists of nuclear envelope which separates nucleus from cytoplasm
  • Contains nucleolus which synthesises ribosomes
  • Found in all cells except red blood cells
  • Contains hereditary material
  • Controls all cell activities
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4
Q

Define cytoplasmic streaming

A

Cytoplasmic streaming is the movement of cytoplasm within a cell, which aids in the transport of materials and organelles around the cell

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5
Q

Describe structures and functions of rough endoplasmic reticulum

A
  • System of flattened membrane-bound sacs
  • Protein synthesis
  • Polypeptide chains synthesised by ribosomes are folded in RER
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6
Q

Describe structures and functions of smooth endoplasmic reticulum

A
  • Consists of fine tubules
  • Lipid synthesis
  • Detoxification of drugs and poisons
  • Storage and release of calcium ions
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7
Q

Describe structures and functions of Golgi apparatus

A
  • Consists of stacks of flattened membrane-bound sacs
  • Chemically modifies products received from ER, packages them, then sends them to destinations in/out of cell via vesicles
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8
Q

Describe structures and functions of lysosomes

A
  • Small, spherical vesicles
  • Contains hydrolytic enzymes (lipases, proteases, nucleases)
  • Digest materials in cell by phagocytosis
  • Digest worn-out organelles by autophagy
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9
Q

Describe structures and functions of animal vacuoles

A
  • Fluid-filled sac bound by single membrane
  • Formed by pinching-off part of cell membrane or by enlargement of vesicle from Golgi apparatus
  • Relatively smaller and exist temporarily
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10
Q

Describe structures and functions of plant vacuoles

A
  • Large central vacuole is permanent and occupies 80% of cell volume
  • Enclosed by single, partially permeable membrane called tonoplast
  • Filled with cell sap, a solution of dissolved substances
  • Storage of nutrients like proteins and inorganic ions
  • Disposal sites for metabolic by-products that would endanger the cell if accumulated in cytosol
  • Contains pigments that give colour
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11
Q

Describe structures and functions of mitochondria

A
  • Rod shaped or cylindrical
  • Bounded by double membrane
  • Involved in aerobic respiration
  • ATP is the energy molecule in organisms
  • Abundant in metabolically active cells
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12
Q

Describe structures and functions of chloroplasts

A
  • Bounded by double membrane
  • Contains chlorophyll, thylakoids, stroma
  • Site of photosynthesis
13
Q

Describe structures and functions of ribosomes

A
  • Small and round
  • Occur as free ribosomes suspended in cytosol or bound ribosomes bound to RER
  • Site of polypeptide synthesis
  • Free ribosomes make proteins that function within cytosol
  • Bound ribosomes make proteins destined for insertion into membranes, packaging within lysosomes, or for export out of cell
14
Q

Describe structures and functions of centrioles

A
  • Small, hollow cylinders
  • Occurs in pairs
  • Only found in animal cells
  • Involved in cell division
15
Q

What are the non-membranous organelles

A
  • Ribosomes
  • Centrioles
16
Q

Which organelles can only be seen under an electron microscope

A
  • RER
  • SER
  • Golgi apparatus
  • Lysosomes
  • Mitochondria
  • Ribosomes
  • Centrioles
16
Q

Describe protein synthesis and secretion

A
  • Polypeptide chains are synthesised at the ribosomes
  • Synthesised polypeptide chains are then folded at the RER
  • Transport vesicles containing substances made by the ER are pinched off
  • Transport vesicles then fuse and release their substances into the Golgi apparatus
  • Substances are chemically modified and packaged in Golgi apparatus
  • Secretory vesicles that contain these substances are pinched off the Golgi apparatus
  • ATP provides energy for secretory vesicles to move towards and fuse with the cell membrane, releasing substances outside the cell by exocytosis
17
Q

Describe the adaptations and functions of a red blood cell

A
  • No nucleus
  • Biconcave shape
  • Presence of haemoglobin
  • No nucleus allows for more haemoglobin to be packed in cell
  • Biconcave shape increases SA:V ratio to increase rate of gaseous diffusion
  • Haemoglobin allows cell to carry oxygen
17
Q

Describe the adaptations and functions of a root hair cell

A
  • Long and narrow extension
  • Increases SA:V ratio, which increases rate of diffusion and osmosis
17
Q

Describe the formation of lysosomes

A
  • Enzyme contents are synthesised at the RER
  • Transport vesicles transport the synthesised enzymes to Golgi apparatus for further processing
  • Vesicle containing the processed enzymes buds off from Golgi apparatus, forming a lysosome
18
Q

What is cell specialisation

A

It is when different cells have different adaptations to perform different specific functions

19
Q

Describe the adaptations and functions of a muscle cell

A
  • Elongated cylinder
  • Contains many nuclei and mitochondria
  • Mitochondria provides energy needed for cell contraction
19
Q

State the complexity table from least complex

A
  • Macromolecule
  • Organelle
  • Cell
  • Tissue
  • Organ
  • Organ system
20
Q

Which organelles are bounded by double membrane

A
  • Mitochondria
  • Chloroplasts