2.1.1 - Cells Flashcards

1
Q

Nucleus

A
  • Comprised of nuclear envelope with nuclear pores, nucleolus and DNA molecules
  • It contains coded genetic information in the form of DNA molecules
  • Controls the activities of the cell
  • DNA associates with proteins called histones to form a complex called chromatin. Chromatin coils and condenses to form structures known as chromosomes
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2
Q

Nucleolus

A
  • Area within the nucleus
  • Responsible for producing ribosomes
  • It is composed of proteins and RNA
  • RNA is used to form rRNA which is then combined with proteins to form ribosomes
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3
Q

Nuclear envelope

A
  • Double membrane
  • Protects DNA from damage
  • Has nuclear pores
  • The pores allow substances to move in and out of the nucleus
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4
Q

Mitochondria

A
  • Site of aerobic respiration
  • ATP produced
  • Release energy
  • Double membrane
  • Inner membrane highly folded to form cristae
  • Fluid interior is called matrix
  • Membrane forming the cristae contains the enzymes used in aerobic respiration
  • Contains small amount of DNA - can produce their own enzymes and reproduce themselves
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5
Q

Ribosome

A
  • Floats freely in the cytoplasm or is attached to the RER
  • Not surrounded by a membrane
  • Site of protein synthesis
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6
Q

Lysosome

A
  • Round organelle surrounded by a membrane
  • Contains hydrolytic/digestive enzymes: Kept separate from cytoplasm by the membrane
  • Responsible for breaking down waste material (cells/ pathogens)
  • Programmed cell death or apoptosis
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7
Q

Vesicles

A
  • A small fluid filled sac surrounded by a membrane

- Transports substances in and out of the cell, via the cell surface membrane and between organelles

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8
Q

Golgi apparatus

A
  • Group of flat fluid filled sacs
  • Modifies proteins (add carbohydrates/sugars)
  • Repackages them into vesicles
  • Makes lysosomes
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9
Q

Endoplasmic reticulum

A
  • A network of membranes enclosing flattened sacs called cisternae
  • RER: Ribosomes bound to surface
  • RER folds and processes proteins, packages them into vesicles
  • SER : Synthesises and processes lipids/ carbohydrates/steroid hormones
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10
Q

Centrioles

A
  • Component of cytoskeleton
  • Small hollow cylinders containing microtubules
  • Two associated centrioles form the centrosome, which is involved in the assembly and organisation of the spindle fibres
  • In organisms with flagella and cilia, centrioles play a part in positioning them
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11
Q

Cilia

A
  • Small hairlike structure found on the membrane
  • Moves substances across the cell surface
  • Stationary cilia/ mobile cilia
  • Two central microtubules surrounded by nine pairs of microtubules
  • Pairs of parallel microtubules slide over each other causing the cilia to move in a beating motion
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12
Q

Flagella

A
  • Tail-like structure
  • Enables cell to move
  • In some cells they are used as a sensory organelle detecting changes in the cell’s environment
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13
Q

Cell wall

A
  • Made of cellulose
  • Freely permeable
  • Substances can pass in and out
  • Gives it shape
  • Contents of the cell press against cell wall making of rigid
  • Defence mechanism against invading pathogens
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14
Q

Vacuole

A
  • Membrane lined sac
  • Contains cell sap
  • Large permanent vacuole
  • Important in maintenance of turgor
  • Membrane of vacuole(tonoplast)it is selectively permeable
  • Animal cells (small and transient)
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15
Q

Chloroplast

A
  • Responsible for photosynthesis
  • Found in green parts of plants
  • Double membrane
  • Fluid enclosed in chloroplast(stroma)
  • Internal network of membranes which form flattened sacs called thylakoids
  • Several thylakoids stacked together(granum)
  • Grana are joined together by membranes called lamellae
  • Grana contain chlorophyll pigments
  • Starch present as starch grains
  • Contain DNA and proteins
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16
Q

Cytoskeleton

A
  • Present throughout cytoplasm
  • Network of fibres
  • Microfilaments: Contractile fibres made from protein actin. Cell movement and cell contraction during cytokinesis
  • Microtubules : Globular tubulin polymerises to form tubes that form a scaffold-like structure that determines the shape of the cell
  • Intermediate fibres - These fibres give mechanical strength to cells and help maintain integrity.
17
Q

Function of cytoskeleton

A
  • Maintain shape
  • Movement of vesicles
  • Enabling cell movement
  • Provides stability
  • Movement of RNA or chromosomes
  • Hold organelles in place
  • Provide mechanical strength
18
Q

Eukaryotic cells

A

Eukaryotic cells are cells with a nucleus and other membrane-bound organelles

19
Q

Prokaryotic cells

A

Cells with no membrane-bound nucleus

20
Q

P vs E(Size)

A
  • 1 to 10 micrometer

- 10 to 100 micrometer

21
Q

P vs E(Nucleus)

A
  • Not present

- Present

22
Q

P vs E (DNA)

A
  • Circular, one main molecule of DNA, additional DNA can be found in plasmids, genes on the chromosomes are often grouped into operons
  • Linear, DNA associated with histone proteins, additional DNA found in mitochondria and chloroplast
23
Q

P vs E (Organelles)

A
  • Non membrane-bound

- Both membrane-bound and non membrane-bound

24
Q

P vs E (Cell wall)

A
  • Peptidoglycan

- Chitin in fungi, Cellulose in plants, Not present in animals

25
P vs E(Ribosomes)
- Smaller 70S | - Larger 80S
26
P vs E (Cytoskeleton)
- Present | - Present (more complex)
27
P vs E (reproduction)
- Binary fission | - Asexual or Sexual
28
P vs E (cell type)
- Unicellular | - Unicellular and multicellular
29
Protein production
- Nucleus produces mRNA - Proteins are synthesised by the RER - They are packaged into vesicles - The vesicles travel along the cytoskeleton to the Golgi apparatus - The Golgi apparatus modifies the proteins(carbohydrates added) - They are then packaged into secretory vesicles - Secretory vesicles transport the protein to the plasma membrane - The vesicles fuse with plasma membrane and the contents are released by exocytosis.
30
Organelles of plant cells that are not in animal cells
- Cellulose cell wall - Chloroplast - Large permanent vacuole or tonoplast
31
Organelle present in animal cells but not in plant cells
- Centrioles | - Lysosomes
32
Why can’t light microscope observe small organelles
- They are too small - Resolution of light microscope not high enough - Wavelength of light too long
33
What feature of a eukaryotic cell would a prokaryotic cell not have
- Nucleus - Mitochondria - Endoplasmic reticulum - Golgi body
34
Feature of prokaryotic cell not found in eukaryotic cell
- Plasmid - Nucleoid/ Free DNA - 70S ribosomes
35
P vs E ( Diameter of cell)
- 0.5 to 5 micrometer | - 20- 40 micrometer
36
Two processes that rely on cytoskeleton for movement
- Chromosomes (Cell division) | - RNA ( Protein synthesis)
37
Why does the nuclear envelope have pores
- To allow movement of substances in or out of the nucleus | - RNA moves to the ribosomes