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AS Biology > Ch 1: Cells & Microscopy > Flashcards

Ch 1: Cells & Microscopy Flashcards

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1
Q

What is a cell

A

The basic structural and functional unit of an organism

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2
Q

What is the role of the cell membrane

A

To control the substances that enter or leave the cell

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3
Q

What are the two key types of microscopes

A
  • light microscope

- electron microscope (more advanced)

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4
Q

What are the parts of a microscope (8)

A
  • Eyepieces (ocular lens)
  • Trinocular (camera) port
  • Objective lens
  • Stage
  • Condenser
  • Light bulb
  • Coarse focusing
  • Fine focusing
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5
Q

Function of eyepieces

A

Key definition: Focuses image from the objective to the eye.

Look through as an observer to see what you want to observe in the microscope (always 10x magnification), both eyes should be open for an accurate observation

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6
Q

Function of objective lens

A

Key definition: collects light passing through the specimen and produces a magnified image.

Magnifies an image, either by 10x, 40x and 100x magnification

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7
Q

Function of the stage

A

Where you put the slide (containing specimen)

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8
Q

Function of condenser lens

A

Key definition: focuses the light onto the specimen held between the cover slop and slide.

Concentrates light onto the slide so it flows through and illuminates the specimen

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9
Q

Fine/Coarse focusing

A

Changes and adjusts the resolution of the image

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10
Q

what is magnification

A

magnification is the number of times by which an image is bigger than the actual object

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11
Q

what is resolution

A

the ability to distinguish between two objects which are very close together. A higher resolution means more detail can be seen

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12
Q

Formula for magnification

A

Magnification = Image size/actual size

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13
Q

How big is a micrometer

A

10^-6 of a meter (mm is 10^-3of a meter)

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14
Q

How big is a nanometer

A

10^-9 of a meter (mm is 10^-3 of a meter)

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15
Q

how to observe cellular material in more detail

A
  • specimens can be prepared for viewing under a light microscope
  • Samples need to be thin enough to allow light to pass through
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16
Q

Biological drawings rules

A
  • The drawing must have a title
  • The magnification under which the observations shown by the drawing are made must be recorded
  • A sharp HB pencil should be used (and a good eraser!)
  • Drawings should be on plain white paper
  • Lines should be clear, single lines (no thick shading)
  • No shading
  • The drawing should take up as much of the space on the page as possible
  • Well-defined structures should be drawn
  • The drawing should be made with proper proportions
  • Label lines should not cross or have arrowheads and should connect directly to the part of the drawing being labelled
  • Label lines should be kept to one side of the drawing (in parallel to the top of the page) and drawn with a ruler
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17
Q

What is an eyepiece graticule

A
  • it is used to measure the size of the object when viewed under a microscope
  • it is a disc placed in the eyepiece with 100 divisions, this has no scale
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18
Q

What is a stage micrometer

A
  • used to measure the size of the object when viewed under a microscope
  • a slide with a very accurate scale in micrometres (µm), it is usually in 10 µm divisions, so 1 mm divided into 100 divisions
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19
Q

How to calibrate a microscope

A

To know what the divisions equal at each magnification the eyepiece graticule is calibrated to the stage micrometer at each magnification

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20
Q

How to find the length of a graticule division

A

1 graticule division = number of micrometres ÷ number of graticule division

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21
Q

How to calculate total magnification

A

eyepiece lens magnification x objective lens magnification

= total magnification

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22
Q

How is resolution and magnification affected by wavelength of light

A
  • The resolution of a light microscope is limited by the wavelength of light
  • As light passes through the specimen, it will be diffracted
  • The longer the wavelength of light, the more it is diffracted and the more that this diffraction will overlap as the points get closer together
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23
Q

Why do electron microscopes have a much higher resolution and magnification than a light microscope

A
  • Electron microscopes have a much higher resolution and magnification than a light microscope as electrons have a much smaller wavelength than visible light
  • This means that they can be much closer before the diffracted beams overlap
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24
Q

What is a photomicrograph

A

images obtained from a light microscope, these are used for specimens above 200 nm (a bacteria cell is about 1000 nm)

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25
Q

What is the cell membrane (purpose and characteristics)

A
  • All cells are surrounded by a cell surface membrane which controls the exchange of materials between the internal cell environment and the external environment
  • The membrane is described as being ‘partially permeable’
  • The cell membrane is formed from a phospholipid bilayer of phospholipids spanning a diameter of around 10 nm
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26
Q

What is the cell wall (purpose and characteristics)

A
  • Cell walls are formed outside of the cell membrane and offer structural support to cell
  • Structural support is provided by the polysaccharide cellulose in plants, and peptidoglycan in most bacterial cells
  • Narrow threads of cytoplasm (surrounded by a cell membrane) called plasmodesmata connect the cytoplasm of neighboring plant cells
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27
Q

what are the characteristics of the nucleus

A
  • relatively large
  • separated from the cytoplasm by a double membrane called the nuclear envelope which has many pores (for travel of mRNA, ribosomes, enzymes and signaling molecules
  • contains chromatin
  • at least one more darkly stained regions can be observed (nucleolus, site of ribosome production)
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28
Q

What are the characteristics of chloroplasts

A
  • Larger than mitochondria, also surrounded by a double-membrane
  • Membrane-bound compartments called thylakoids containing chlorophyll stack to form structures called grana
  • Grana are joined together by lamellae (thin and flat thylakoid membranes)
  • Also contain small circular pieces of DNA and ribosomes used to synthesise proteins needed in chloroplast replication and photosynthesis
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29
Q

Purpose of chloroplasts

A

Chloroplasts are the site of photosynthesis:

  • The light-dependent stage takes place in the thylakoids
  • The light-independent stage (Calvin Cycle) takes place in the stroma
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30
Q

properties of large permanent vacuole

A
  • sac in plant cells surrounded by the tonoplast, a selectively permeable membrane
  • vacuoles in animal cells are not permanent and small
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31
Q

purpose and characteristics of vesicles

A

membrane bound sac for transport and storage

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32
Q

purpose and characteristics of microvilli

A

cell membrane projections that increase the surface area for absorption

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33
Q

purpose and characteristics of flagella

A
  • similar in structure to cilia, made of longer microtubules

- contract to provide cell movement for example in sperm cells

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34
Q

where do all new cells come from

A

all new cells arise from already existing cells

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35
Q

what is a cell

A

a cell is the basic structural and functional unit of an organism

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36
Q

what does the cytoplasm contain

A
  • cytosol (semi fluid)

- organelles (suspended in cytosol)

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37
Q

what is an organelle

A

an organised structure within a cell in which specialised functions are carried out

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38
Q

what is the protoplasm

A

the living part of the cell, the nucleus+cytoplasm

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39
Q

what is a protoplast

A

a plant/fungal cell with its cell wall removed

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40
Q

what is the structure of a nucleus

A
  • largest organelle
  • may have mutiple nucleoli
  • 10 micrometer
  • spherical in a drawing (3D)
  • round in a micrograph
  • enclosed by 2 membranes
  • outer membrane connected/continuous to rough endoplasmic reticulum
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41
Q

what is the nuclear envelope

A
  • made up of double membrane (outer and inner)
  • encloses nucleus
  • they join to form the nuclear pore
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42
Q

what is the nuclear pore

A
  • enclosed by nuclear proteins
  • where the double membrane meets
  • controls entry and exit of material through the nucleus
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43
Q

what are nucleoli (singular nucleolus

A
  • irregular shape
  • may have multiples in nucleus
  • synthesizes ribosomes and rRNA
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44
Q

What are the characteristics and properties of lysosomes?

A
  • specialist forms of vesicles which containhydrolytic enzymes (enzymes that break biological molecules down)
  • break down waste materials such as worn out organelles, used extensively by cells of the immune system and in apoptosis (programmed cell death)
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45
Q

What are the key features ofan animal cell electron micrograph

A
  • Golgi apparatus
  • rough endoplasmic reticulum
  • nucleus
  • mitochondria

Picture: https://cdn.savemyexams.co.uk/wp-content/uploads/2020/10/Animal-Cell-micrograph-2.png

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46
Q

What are the key features of a plant cell electron micrograph?

A
  • -Mitochondria
  • Chloroplast
  • Vacuole
  • cell wall
  • Nucleus
  • nucleolus
  • image:https://cdn.savemyexams.co.uk/wp-content/uploads/2020/10/Plant-Cell-Micrograph-2.png
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47
Q

What structures do animal cells have?

A
  • centrosome with two centrioles close to the nucleus and at right angles to each other
    -Lysosome
  • mitochondrion
  • rough endoplasmic reticulum
    -Nucleus(with nucleolus,chromatin,nuclear
    pore, nuclear envelope 2x membrane
    -smooth endoplasmic reticulum
    -Cytoplasm
  • cell surface membrane
    -Ribosomes
    -microtubules radiating from centrosome
    -Golgi body
    -Golgi vesicle
    -microvilli
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48
Q

What structures do plant cells have?

A
  • Plasmodesma
  • vacuole (with cell sap and tonoplast)
  • cell surface membrane(pressed against cell wall)
  • smooth endoplasmic reticulum
  • nucleus (with nuclear pore,nucleolus, chromatin, nuclear envelope)
  • rough endoplasmic reticulum
  • microtubule
  • Ribosomes
  • chloroplast (with envelope and grana
  • Mitochondrion
  • Cytoplasm
  • Golgi body
  • golgi vesicle
  • Chloroplast
  • middle lamella
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49
Q

Why do organisms require a constant supply of energy?

A

All organisms require a constant supply of energy to maintain their cells and stay alive

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50
Q

Why is energy required for anabolic reactions in cells?

A

For building larger molecules from smaller molecules

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51
Q

Why is energy required for movement of substances?

A

To move substances across the cell (active transport) or to move substances within the cell

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52
Q

What is energy required for in animals?

A
  • For muscle contraction, to coordinate movement at the whole organism level
  • in the conduction of nerve impulses, as well as many other cellular processes
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53
Q

What are nucleotides?

A

Complex chemicals made up of an organic base, a sugar and a phosphate. They are the basic units from nucleic acids DNA and RNA are made

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54
Q

What is the general cellular structure of prokaryotes?

A
  • their genetic material is not packaged within a membrane-bound nucleus and is usually circular (eukaryotic genetic material is packaged as linear chromosomes)
    -Prokaryotes lack membrane-bound organelles
  • they are many (100s/1000s)of times smaller than eukaryotic cells
  • their ribosomes are structurally smaller (70S)in comparison to those found in
    Eukaryotic cells (80S)
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55
Q

Which structures are always found in prokaryote cells

A
  • Cell wall (containing peptidoglycan)
  • cell surface membrane
  • Cytoplasm
  • Circular DNA
  • Ribosomes
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56
Q

Which structures are sometimes found in prokaryote cells

A
  • flagellum (for motion)
  • capsule (for protection)
  • Infolding of cell membrane to carry out photosynthesis or nitrogen fixation
  • Plasmid (small circle of DNA)
  • Pili (for attachment to other cells or surfaces; involved in sexual reproduction)
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57
Q

What sizes are prokaryotes?

A

1.5-10 micrometer

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58
Q

What size are eukaryotes?

A

10-100 micrometer (red blood cells are the exception with a size of 7 micrometers)

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59
Q

What genome do prokaryotes have?

A

DNA circular with no proteins, in the cytoplasm

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60
Q

Which genome do eukaryotes have?

A

DNA is associated with histones (proteins) formed into chromosomes

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61
Q

How does cell division happen in prokaryotes

A

Occurs by binary fission, no spindle involved

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62
Q

How does cell division happen in eukaryotes

A

Occurs by mitosis or meiosis and involves a spindle to separate chromosomes

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63
Q

what size ribosomes do prokaryotes have?

A

70S ribosomes

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64
Q

what size ribosomes do eukaryotes have

A

80S ribosomes

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65
Q

What kind of organelles do prokaryotes have?

A

-Very few membrane-bound organelles

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66
Q

What type of organelles do eukaryotes have?

A

Numerous types of organelles:

  • Membrane-bound single membranes
  • lysosomes
  • Golgi complex
  • Vacuoles
  • double membranes
  • Nucleus
  • mitochondria
  • Chloroplast no membrane
  • Centrioles
  • Ribosomes
  • Microtubules
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67
Q

What are prokaryotes cell walls made of?

A

Made of peptidoglycan (polysaccharide and amino acids) and murein

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68
Q

What type of cell walls do eukaryotes have?

A

Present in plants (made of cellulose or lignin)and fungi (made of chitins similar to cellulose but contains nitrogen)

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69
Q

What are viruses?

A

Viruses are non-cellular infectious particles that straddle the boundary between ‘living’and ‘non-living’

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70
Q

What is the structure of viruses?

A

-They are relatively simple in structure, much smaller than prokaryotic cells (with diameters between 20 and 300 nm)
- they have a nucleic acid core (their genomes are either DNA or RNA and can be single or double-stranded)
- a protein coat called a capsid
- an envelope (a membrane-like outer layer),
Made up of phospholipids may be present in some viruses

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71
Q

What is a virus envelope

A
  • outer layer formed usually from the membrane

- made of phospholipids

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72
Q

How do viruses reproduce?

A
  • it is parasitic
  • infecting living cells and using their ribosomes with DNA and RNA inside to produce new viral particles
  • the virus converts the host cell into a ‘viral production factory ‘
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73
Q

Why/how are light microscopes and electron microscopes different?

A

Electron microscopes differ from light microscopes because they produce the image of a specimen using a beam of electrons. Visible light is used in the light microscopes to magnify images of tiny areas of materials or biological specimen. Electrons have a much shorter wavelength than light and this allows electron microscopes to produce higher resolution images

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74
Q

How big are viruses?

A

most viruses are 20-300 nanometers

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75
Q

what is the structure of the smooth endoplasmic reticulum?

A
  • no ribosomes

- tubular cisternae

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76
Q

what is the function of the rough endoplasmic reticulum

A

to synthesize proteins to be transported outwards towards the cell surface membrane/away from the nucleus

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77
Q

where do materials travel through in the endoplasmic reticulum

A

the cisternae transport the materials in the liquid space inside

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78
Q

what is the function of the smooth endoplasmic reticulum

A

to synthesize lipid and steroids to be transported outwards towards the cell membrane/away from the nucleus

79
Q

what is a ribosome

A

structure made up of rRNA + protein synthesized in the nucleus

80
Q

what is the structure of ribosomes

A
  • made up of 2 subunits; big subunit and small subunit
  • it is the smallest organelle
  • there are two sizes: 80S and 70S
  • found attached to rough endoplasmic reticulum (80S), or in mitochondria+chloroplasts (70S) or free in the cytosol
81
Q

what is the function of ribosomes

A
  • to synthesize proteins
  • if the ribosomes are free in the cytosol, the proteins are used in the cytosol
  • if the ribosome is attached to the RER the proteins are to be transported to organelles outside the cytosol (cell membrane, nucleus, cell wall, other organelles)
82
Q

what is the structure of the Golgi apparatus/body/complex

A
  • made up of cisternae and Golgi vesicles
  • from top view appears to be disk shaped structures stacked ontop of each other
  • from side view apears to be long u shapes
  • top cisterna (called the inner maturing face) is concave
  • bottom cisterna (called outerforming face) is convex
83
Q

how are the Golgi apparatus cisternae formed

A
  • pinched off/budding off from the ends of the endoplasmic reticulum cisternae
  • move towards the cell membrane
  • then transport vesicles fuse together to form the long cisternae of the Golgi apparatus
84
Q

what is the function of the Golgi apparatus

A

it is the center of collection, modification, transportation and distribution
-it may also secrete mucus/wax/gum

85
Q

what does th Golgi apparatus modify

A

the golgi apparatus changes glycoproteins to glycolipids through glycosylation

86
Q

how does the golgi apparatus transport and distribute

A

after modification, the golgi vesicle pinches off from the edge of the cisterna of the outer formingface for transportation and distribution and fuse with the cell surface membrane to be released/become part of the membrane or to be used inside the cell
- the golgi vesicle (secretory vesicle) may also secrete mucus/wax/gum

87
Q

what is a lysosome

A

lysosomes are golgi vesicles that are not secretory vesicles

88
Q

what is the structure of a lysosome

A
  • 0.5 micrometers in length

- a fluid-filled sac

89
Q

what are the characteristics/properties of lysosomes

A
  • they contain many strong hydrolytic enzymes used for the breakdown of carbohydrates, proteins, lipids and nucleic acid
  • they can work under acidic conditions
  • only found in animal cells, not plant cells
90
Q

how are lysosomes formed

A

they are formed by pinching/budding off the Golgi apparatus

91
Q

what is the function of lysosomes

A
  • digests materials taken in by endocytosis
  • digest specific material outside the cell
  • autophagy
  • autolysis
92
Q

what is endocytosis

A

a process where the cell takes in foreign substances

93
Q

what is the process of endocytosis

A
  • substance taken in
  • surrounded by phagocytic vacuole
  • lysosome fuses with vacuole
  • substance is hydrolysed (digested)
  • digested substance assimilated
  • undigested remains exit the cell through exocytosis
94
Q

what specific materials do lysosomes digest outside the cell?

A

bone cartilage

  • to be replaced with new bone or to be remodeled after bone injury
  • the enzyme used is lysosyme

digestion of protective coat layer of female egg cell by sperm cell

  • for fertilization
  • the lysosome here is called an acrosome
95
Q

what is autophagy

A

the digestion of old, unwanted organelles from the cell itself

96
Q

what is the process of autophagy

A
  • unwanted organelle surrounded by phagocytic vacuole
  • lysosome fuses with vacuole to form phagolysosome
  • organelle is hydrolysed (digested)
  • digested substance assimilated
  • undigested remains exit the cell through exocytosis
97
Q

what is autolysis

A

autolysis is a process in which a cell will self destroy/breakdown its whole self

98
Q

why does autolysis happen

A

autolysis hapens when a cell is uneeded and needs to be recycled

99
Q

in which cells can autolysis occur

A

autolysis only happens in a few cells such as

  • tadpole tail cells
  • extra uterus wall after pregnancy
  • muscle degeneration
100
Q

where is mitochondria thought to originate from

A

endosymbiotic aerobic bacteria

101
Q

where do mitochondria now come from

A

mitochondria come fromalready existing mitochondria inside the cell

102
Q

what is the structure of mitochondria

A
  • double membrane (outer and inner)
  • width is around 1 micrometer and diameter is 1.5-10 micrometer
  • the shape can be from spherical to highly elongated
  • inside is made up of the matrix and cristae, phosphate granules and 70S ribosomes
  • nail like structures (stalked particle) along the surface of the inner membrane for ATP synthesis
103
Q

what is the matrix (mitochondria)

A
  • fluid filled space (ground substance)

- where other material is suspended in, in the mitochondria

104
Q

what are cristae

A

(singular- crista)

-finger like projection (not villi/microvilli)

105
Q

what is the function of the mitochondria

A
  • the mitochondrion is the powerhouse of the cell

- synthesizes ATP through aerobic respiration to do the cell’s work

106
Q

how/where does the mitochondria synthesize ATP

A
  • the stalked particle contains the enzyme that catalyses the synthesis of ATP from a biochemical reaction (ADP + Pi -> ATP)
  • the site of ATP synthesis is the inner membrane in the mitochondria
107
Q

how do mitochondria appear in micrographs

A

sausage like structures with finger like projections/shadowed in the inside

108
Q

what is ATP

A
  • it is a universal (all cells in all organisms use it) energy carrier/source of energy that carries energy currency from Energy yielding reactions to Energy requiring reactions
  • it is a small, soluble, intermediate (made from reaction to react further) molecule
  • it is the energy currency of the cell, cell trades/donates ATP to energy required reactions to do work
109
Q

how does ATP release energy

A

ATP releases energy through hydrolysis (ATP -(hydrolysis)> energy + ADP + Pi)

110
Q

what is the role of ATP in cells

A
  • anabolic reactions
  • active transport
  • movement/locomotion
111
Q

what are anabolic reactions

A

the building up/synthesis process of complex compounds from simple compounds

112
Q

what are examples of anabolic reactions

A
  • photosynthesis
  • DNA synthesis (nucleotides joining up to form DNA)
  • activation of glucose in respiration
  • protein synthesis (amino acids joining up to form polypeptides
  • glycogenesis (synthesis of glycogen)
  • starch synthesis (glucose joins up to form starch
  • lipid synthesis (glucose joins up to form triglyceride
113
Q

what is an example of active transport

A

sodium potassium pump

114
Q

what is an example of movement/locomotion that requires ATP

A
  • muscle contraction
  • movement/beating of cilia/flagella
  • endocytosis/exocytosis
  • movementof vesicles on microtubules
115
Q

what is the structure of a microtubule

A
  • long rigid hollow tube
  • 25 nanometer in diameter
  • made up of protein subunits (tubulin)forming rings of protofilaments
  • 1 ring = 13 protofilaments
116
Q

what are tubulin dimers made up of

A

alpha tubulin +beta tubulin = tubulin dimer

117
Q

what are protofilaments made up of

A

tubulin dimers join ends to form protofilaments

118
Q

where can microtubules be found

A

in the cytoplasm of the cell

119
Q

where are microtubules synthesized

A

they are synthesized in the MTOC (MicroTubule Organizing Center)

120
Q

what is the function of microtubules

A
  • to form the cytoskeleton of the cell
  • for anchorage
  • monorail
  • building block of centriole, cilia and flagella
121
Q

what is the cytoskeleton

A
  • a complex network of interlinking microtubules, intermediate filaments and microfilaments
  • gives shape and support to cell
  • continuosly being dissembled, reassembled and rearranged (e.g. during exocytosis,endocytosis, mitosis and cell movement like amoebic movement of white blood cells
122
Q

what is the purpose of microtubule anchorage

A

anchor organelles to fixed locations in the cell

123
Q

what isthe purpose of the microtubule monorail

A

direct intracellular movement of organelles and vesicles

124
Q

what is the structure/characteristics and properties of centrioles

A
  • small hollow cylindrical structures made from microtubles found in centrosome (area near nucleus)
  • always occur in a pair perpendicular to each other
  • formed from 9 triplets of microtubules
  • length of 500 nanometers
  • width of 200 nanometers
125
Q

what is the function of the centrioles

A
  • form pores during mitosis and meiosis

- form bases of cilia and flagella

126
Q

what is a centrosome

A

centrosome is an organelle in plant and animal cells situated near the nucleus

127
Q

what are the functions of a centrosome

A
  • synthesizes microtubules
  • assembles microtubules for the formation of other structures made of microtubules (e.g. centriole, spindle fibres, cilia, flagella, cytoskeleton microtubules)
  • the centrosome acts as the MTOC (MicroTubule Organizing Center)
128
Q

what is the singular word name for cilia cells

A

cilium

129
Q

what is the structure of the cilia

A
  • whiplike structure projecting outwards from the surface of some animal cells and the cells of many unicellular organisms
  • the base of the cilia is a centriole (basal body) for anchorage by microtubules
  • the axonemeis the cylindrical structure inside the cell surface membrane of the cilia made of microtubules
130
Q

what is the arrangement of microtubules in the cilia

A
  • the microtubules have a 9+2 arrangement
  • the A and B microtubules join to form 9 microtuble doublets with 2 singlet microtubules in the center (this forms the outer ring of the cilia)
  • the A microtubule has an outer arm and an inner arm made up of dynein protein arm
  • the B microtubule is an incomplete ring as it attaches to the A microtubule
  • A microtubule has 13 protofilaments but the B microtubule is an incomplete ring with only 10 protofilaments only
131
Q

what is the comparison in length between cilia and flagella

A
  • cilia is shorter

- flagella is longer

132
Q

what is the difference in the number of organelle per cell between cilia and flagella

A
  • there are many cilia per cell

- there are only one or two flagella per cell

133
Q

how do cilia and flagella move/”beat”

A

beating is due to dynein (protein) arms contact and move along neighbouring B microtubules

134
Q

what is the comparison in movement between cilia and flagella

A
  • cilia have a beating/rowing motion in one direction

- flagell have a wavelike motion from the base outward

135
Q

what is the difference in function between cilia and flagella

A
  • the purpose of cilia are to move the cell/fluid around the cell
  • the purpose of flagella are to move the cell through locomotion
136
Q

what is the singular name for microvilli

A

microvillus

137
Q

what is the structure of microvilli

A
  • thin fingerlike folding of the cell surface membrane/brush border of the cell
  • encloses the cytoplasm and (actin) microfilaments (thinner than microtubules)
138
Q

what is the function of microvilli

A

to increase surface area to volume ration for the absorption of H2O and digested food in the intestine

139
Q

what are villi (singular villus)

A
  • finger-like structure prohecting into the lumen from the lining of the small intestine
  • not the same as microvilli
  • villi are lined with many cells that have microvilli
140
Q

what is the thickness comparison between cilia and microvilli

A
  • cilia are longer and thinner

- microvilli are shorter and thicker

141
Q

what is the difference in ends between cilia and microvilli

A
  • cilia have tapering (sharp) ends

- microvilli have blunt ends

142
Q

what is the difference in motility between cilia and microvilli

A
  • cilia are motile(move to create current) for mucus/move cell
  • microvilli are non-motile, they do not move and only absorb substances
143
Q

what is the difference in microtubule/microfilament arrangement between cilia and microvili

A
  • cilia have a 9+2 microtubule arrangement

- made up of actin microfilaments

144
Q

what is the difference in locations between cilia and microvilli

A
  • cilia cells line airways

- microvilli line the intestines and oviduct

145
Q

where are chloroplasts thought to originate from?

A

endosymbiotic bacteria, anaerobic photosynthetic bacterium, lost some of their genes to host chromosomes

146
Q

what is the structure of chloroplasts

A
  • double membrane form chloroplast envelope
  • thylakoid membranes stack up to form stack of thylakoid called ‘granum’ (plural: grana)
  • the granum are connected by elongated thylakoids called intergranal lamella
  • chloroplasts also have circular DNA, starch grains, lipid droplets and 70S ribosomes and stroma
147
Q

what is the function of chloroplasts

A
  • to carry out photosynthesis
  • light dependent reactions occur in the thykaloid membranes
  • light independent reactions occur in the stroma
148
Q

what are intergranal lamella

A

thin plate-like structures that connect grana in the chloroplast

149
Q

why do light dependent reactionsoccur in the thylakoid membranes in the chloroplasts

A

-to trap light energy by chlorophyll pigments in the thylakoid membranes to convert light energy to ATP

150
Q

how/what light independent reactions occur in the stroma

A

chloroplasts use the ATP to convert CO2 (inorganic molecule) to sugar (C6H12O6, organic molecule)

151
Q

what is the structure/location of the cell wall

A
  • non living rigid structures formed outside the cell surface membrane
  • also found outside fungal (chitin) and bacterial (peptidoglycan) cell surface membrane
  • the plant cell wall consists of 3 possible layers (middle lamella, primary wall and secondary wall) + plasmodesma
152
Q

what is the middle lamella

A

the layer between two adjoining plant cell walls,made up mainly of pectin that acts like a slime/gel

153
Q

what is the primary wall layer in a cell wall

A
  • first wall formed by cell
  • thin and rigid
  • made up of parallel cellulose fibres running through gel-like matrix of complex polysaccharides (hemicellulose + pectin)
  • cellulose fibres are not elastic and have high tensile strength
  • thin single line in micrograph
154
Q

what is the secondary wall layer in the cell wall

A
  • called ‘lignified wall’
  • produced when the cell differentiates
  • extra layers of cellulose added between cell surface membrane and primary wall
  • each layer is made up of parallel cellulose fibres+ hemicellulose+sometimes lignin/cutin/suberin
  • thick double line appearing wall in micrograph
  • the fibres in different directions like cross ply to make the structure stronger
155
Q

what are the layers of root tip

A
  • zoneof cell division
  • zone of cell elongation
  • cell differentiates and specialises in structure and function
156
Q

what is the plasmodesma

A

a cytoplasmic strand (no cell wall) running across plant cellwalls, connecting cytoplam of adjacent cells

157
Q

difference between primary and secondary cell walls in formation

A
  • primary wall formed by newly formed cells

- secondary wall formed from elongating and differentiating cells

158
Q

difference between primary cell wall and secondary cell wall in location

A
  • the primary wall is located between the middle lamella and the cell surface membrane/secondary wall
  • the secondary wall is located between the primary wall and the cell surface membrane
159
Q

what is the difference between primary cell wall and secondary cell wall in the types of cells they are found in

A
  • the primary cell wall is found in all cells

- the secondary cell wall is found in the xylem element, schlerenchyma, epidermal cells and endodermal cells

160
Q

what is the difference between primary cell wall and secondary cell wall in terms of number of layers

A
  • the primary cell wall has 1 layer

- the secondary cell wall has 3 or more layers

161
Q

what is the difference between primary and secondary cell walls in terms of composition

A
  • the primary wall is composed of cellulose, hemicellulose and pectin
  • the secondary cell wall is composed of cellulose, hemicellulose, lignin, cutin, suberin
162
Q

what is the difference between primary and secondary cell walls in terms of cellulose content

A
  • the primary wall has a low cellulose content

- the secondary wall has a high cellulose content

163
Q

is the primary wall pitted

A

no

164
Q

is the secondary cell wall pitted

A

sometimes

165
Q

difference between primary and secondary cell walls in terms of nature

A
  • the primarywall is elastic and can expand

- the secondary wall is rigid and cannot expand

166
Q

what is the function of the cell wall

A
  • mechanical support for individual cell and the plant by means of lignified wall and turgor support
  • protects cells from bursting due to excessive water utake by osmosis
  • provides shape to cell by different orientations of cellulose fibers layers
  • controls movement of materials in and out of the cell (in exam must specify,,see next card)
167
Q

how does the cell wall control the movement of materials in and out of the cell

A
  • apoplast pathway (cel wall to cell wall) for transport of H20 and mineral ions
  • symplast pathway (cytoplasm to cytoplasm)transport materials through plasmodesmata
  • suberin (inside cell wall of root endodermal cells) is waterproof which force water and mineral ions to pass through the membrane and controls movement of material
  • waxy cutin layer forms cutice that is waterproof to reduce water loss by evaporation from the epidermal cell wall surfaces (on leaves and stem surfaces)
168
Q

what is the structure of vacuole/s

A
  • in eukaryotic cells(plant, protozo, animal) usually made up of a large membrane bound sac in the cytoplasm
  • plant cells have a permanent central vacuole surrounded by tonoplast(membrane)
  • animal cell vacuoles are relatively smaller and temporary
169
Q

what do vacuoles contain

A

vacuoles may contain solutionsof pigments, enzymes, sugars, mineral salts, oxygen CO2 and ther organic compounds

170
Q

what are the types of animal cell vacuoles

A
  • phagocytic vacuoles
  • food vacuoles
  • autophagic vacuoles
171
Q

what is the function of plant cell vacuoles

A
  • support (turgor support by osmosis)
  • lysosomal activity (when containing hydrolases)
  • secondary metabolites
  • food reserves
  • waste products e.g. calcium oxalate crystals
  • growth insize (osmotic uptake)
172
Q

what are metabolites stored in the plant cells

A
  • anthocyanin pigments in onion, flower and fruit
  • latex=a milky fluid found in rubber trees and poppy trees. Opium poppy contains morphine from which opium and heroine are obtained (anesthetics)
173
Q

what is the size of red blood cells

A

7micrometers

174
Q

how big are cell surface membranes

A

7nanometers

175
Q

how big are nuclei

A

10micrometers

176
Q

how big are most bacteria

A

1-5 micrometers

177
Q

what is the minimum size the naked eye can see

A

0.1mm/100 micrometers

178
Q

what is the max resolution of a light microscope

A

200nm (max resolution=minimum distance to be seen as 2 seperate objects)

179
Q

what is the max resolution of an electron microscope

A

0.5 nanometers (max resolution=minimum distance to be seen as 2 seperate objects)

180
Q

what is the max magnifictation on a light microscope

A

1,500

181
Q

what is the max magnification of an electron microscope

A

250,000

182
Q

What chemicals are secreted from the secretory vesicles

A
  • Digestive enzymes
  • antibodies
  • mucus
  • hormones
  • wax and guns
183
Q

What are the structures formed when a lysosome fuses with a phagocytic vacuole

A
  • phagolysosome

- secondary lysosome

184
Q

Which cells contain cilia

A

paramecium and ciliated epithelial cells

185
Q

what is the structure of rough endoplasmic reticulum

A
  • circular structurs on the outer surface (ribosomes) to synthesize proteins
  • flattened cisternae
186
Q

what is the endoplasmic reticulum

A
  • a system of highly branched and rejoined network of cisternae interconnected with one another
  • it is made up of the smooth and rough endoplasmic reticulum which are connected to each other
187
Q

what is cisterna/cisternae?

A

membrane bound sacs

188
Q

where is euchromatin found

A

euchromatin (seen as tiny dots in a micrograph) are found around the center of the nucleus

189
Q

where is heterochromatin found?

A

-its arranged at the sides of the nucleus (seen as dark shadows in micrographs) attached to the inside of the nuclear envelope

190
Q

what re the characteristics of heterochromatin?

A
  • not functional/not well expressed
  • not used to make polypeptide
  • more dense and coiled
191
Q

what are the characeristics of euchromatin

A
  • well expressed (its genes are often convertd into polypeptides)
  • less dense and uncoiled
192
Q

What are the two forms of chromatin

A
  • euchromatin

- heterochromatin

193
Q

what is chromatin?

A

exists in the form of DNA wrapped around histone proteins which condense to form chromosomes during mitosis

194
Q

What is DNA?

A

stores all our genetic codes in the form of genes (codes for polypeptides)

AS Biology (11 decks)

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