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Biology Core Idea 1 > Cell Structure > Flashcards

Cell Structure Flashcards

Recognise and describe structure and functions of rough and sooth endoplasmic reticulum, Golgi body, mitochondria, ribosomes, lysosomes, chloroplasts, cell surface membrane, nuclear envelope, centrioles, nucleus and nucleolus

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AP® Biology flashcards Biology 101 flashcards
1
Q

Cell theory

A
  1. Cell is the fundamental unit of structure and function
  2. All cells arise from pre-existing cells by division
  3. Metabolism occurs within cells involving biochemical reactions
  4. Cells contain hereditary information (DNA) passed from parent to daughter cell during cell division
  5. Similar species have cells with similar chemical composition
  6. Living things made up of one or more cells
  7. Activity of organism depends on the total activity of independent cells
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2
Q

Magnification

A

Degree to which the viewed image is larger than the specimen

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3
Q

Resolution

A

Minimum distance whereby two points can be distinguished as separate

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4
Q

Transmission electron microscope

A

Study internal structures

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5
Q

Scanning electron microscope

A

Study surface of cells -> 3D image

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6
Q

Cell fractionation

A

Cells homogenised -> centrifuge separates organelles based on size/density

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7
Q 
Size of organelles (micrometer)
Nucleus
Chloroplast
Mitochondrion
Lysosome
Centrioles
Ribosome
A 
Nucleus: 5-10
Chloroplast: 5-10
Mitochondrion: 1-5
Lysosome: 0.2-1.0
Centrioles: 0.3-0.5
Ribosome: 0.02 (20nm)
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8
Q

Overview of cell structure (4)

A
  1. Plasma membrane/cell surface membrane
  2. Nucleus
  3. Cytoplasm -> Cytosol + organelles + cytoskeleton (framework of protein filaments that give cells their shape)
  4. Cell wall
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9
Q

Nucleus structure

A

Spherical
Nuclear envelope -> double membrane + nuclear pores
Chromosomes/chromatin -> DNA + histones -> euchromatin (loosely coiled, active) + heterochromatin (tightly coiled, not active)

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10
Q

Nucleus function

A
  1. Contains hereditary material (DNA) of organism

2. Controls activities of the cell by regulating protein synthesis

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11
Q

Nucleolus structure

A

Densely stained granules
One or more nucleoli per nucleus
Large concentration of DNA, rRNA and proteins

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12
Q

Nucleolus function

A

Synthesis of rRNA

Assembly of rRNA and ribosomal proteins into ribosomal subunits

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13
Q

Ribosome structure

A

Small subunit + large subunit
Ribosomal RNA + proteins
1. Freely floating in the cytosol (free ribosomes)
2. Attached to outer surface of rER (bound ribosomes)
Prokaryotes -> 70S
Eukaryotes -> 80S

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14
Q

Ribosome function

A

Protein synthesis -> translation of mRNA to protein
Free ribosomes -> proteins that function within cytosol
Bound ribosomes -> proteins for:
1. Secretion out of cell
2. Packaging within organelles
3. Insertion into membrane

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15
Q

Endomembrane system (5)

A
  1. Nuclear envelope
  2. Endoplasmic reticulum (ER)
  3. Golgi Apparatus
  4. Lysosome + Vesicles
  5. Plasma membrane
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16
Q

Nuclear envelope structure + function

A

Perforated by numerous nuclear pores, continuous with ER

Allow regulated passage of substances into or out of the nucleus

17
Q

Endoplasmic reticulum structure

A

Extensive network of membranous tubules and sacs called cisternae

18
Q

Rough endoplasmic reticulum structure

A

Bound ribosomes that stud outer surface -> rough
Signal peptide recognised by signal recognition particle -> bring ribosome to rER -> receptor protein
Cisternae flattened than sER

19
Q

Rough endoplasmic reticulum function (4)

A
  1. Proteins synthesise by bound ribosomes fold into native 3D conformation as they enter cisternal space
  2. Glycosylation (add carbs) to form glycoproteins
  3. Transport of proteins in transport vesicles
    (i) Secretion out of the cell
    (ii) Packaging into organelles
    (iii) Targeted for insertion into plasma membrane
  4. Membrane factory -> grows by adding membrane proteins and phospholipids to own membrane -> transferred in the form of transport vesicles
20
Q

Smooth endoplasmic reticulum structure

A

Appears smooth as it lacks bound ribosomes

Cisternae more tubular

21
Q

Smooth endoplasmic reticulum function (4)

A
  1. Synthesise carbohydrates and lipids
  2. Break down glycogen to glucose in liver cells
  3. Detoxify drugs and poison in liver cells
  4. Store Ca2+ ions in muscle cells
22
Q

Golgi apparatus structure

A

Cisternae + Golgi vesicles
Convex/’cis’ face -> vesicles fuse with it
Concave/’trans’ face -> vesicles pinch off

23
Q

Golgi apparatus function (5)

A

Modifying, sorting and packaging

  1. Glycosylation -> glycoproteins and glycolipids
  2. Modify/cleave existing glycoproteins and glycolipids
  3. Form lysosomes
  4. Produce polysaccharides
  5. Sorts and targets completed material to different parts of the cell or for secretion
24
Q

Lysosome structure

A

Single membrane
Hydrolytic enzymes made by bound ribosomes on rER and processed in GA -> bud off from there
Acidic

25
Q

Lysosome function (4)

A
  1. Digestion of material taken in by endocytosis -> fuse with vesicles/vacuoles
  2. Autophagy -> breakdown of unwanted structures
  3. Release enzymes outside cell by exocytosis
  4. Autolysis -> contents of many lysosomes released within the cell simultaneously

Useful products absorbed into cytoplasm;
Unwanted products released into external medium by exocytosis

26
Q

Mitochondrion structure

A

Rod-shaped
Double membrane
Outer membrane smooth
Inner membrane highly unfolded to form numerous cristae
-> large surface area
Matrix + inter membrane space
Contains 70S ribosomes, circular DNA and enzymes

27
Q

Mitochondrion function

A

Site of cellular respiration -> generate ATP

Krebs cycle in matrix, oxidative phosphorylation in cristae

28
Q

Chloroplast structure

A

Lens shaped
Double membrane
Thylakoids -> grana (stacks)
Chlorophyll, photosynthetic pigments, enzymes, photosystems on thylakoid membrane
Stroma contains circular DNA, ribosomes, enzymes and starch grains

29
Q

Chloroplast function

A

Site of photosynthesis

30
Q

Vacuole structure

A

Large vesicles derived from ER and GA
Fluid-filled sac bound by single membrane
Animal -> smaller and more numerous
Plant -> large central vacuole (tonoplast) which contains cell sap

31
Q

Vacuole function

A

Animal
Food vacuoles formed by phagocytosis enclose material for digestion by lysosome
Fresh water protists -> contractile vacuoles -> pump excess water out

Plant
Maintain turgor pressure
Cell growth -> increase with minimal increase in cytoplasm
Store waste products
Food storage in seeds
32
Q

Microtubule structure

A 
Hollow rods (25nm diameter)
Globular protein (tubulin) -> dimer (2 subunits)
Stiff and run straight course
33
Q

Microtubule function (4)

A
  1. Help maintain shape of cell (cytoskeleton)
  2. Intracellular transport
  3. Chromosome movement in cell division (spindle fibres)
  4. Structural component of centrioles, cilia and flagella
34
Q

Centrioles structure

A

Pair of cylindrical, rod-like structures positioned at right angles
9 triplets of microtubules arranged in a ring
Found in region known as centrosome
Absent in higher plant cells (Microtubule organising centre)

35
Q

Centrioles function

A

Replicate during cell division

Play role in nuclear division by helping to organise formation of spindle fibres, needed for separation of chromosomes

Biology Core Idea 1 (6 decks)

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