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A-Level EDUQUAS Biology > Core Concepts: Cells > Flashcards

Core Concepts: Cells Flashcards

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1
Q

What is the function of the nucleus?

A

Contains the DNA which codes for protein synthesis

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2
Q

What is the function of the nuclear envelope?

A
  • Double membrane surrounding the nucleus
  • Separates the genetic material form the cytoplasm
  • has pores for passage of molecules in and out of nucleus
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3
Q

What is the function of the nuclear pore?

A

passage of molecules in and out of nucleus

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4
Q

What is the function of the nucleolus?

A

Synthesis of rRNA to make ribosomes

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5
Q

What is the structure of ribosomes

A
  • 2 subunits made from rRNA (ribosomal RNA) and protein: small and large subunit
  • either free or attached to RER
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6
Q

What is the function of ribosomes?

A

Protein synthesis

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7
Q

What does RER mean?

A

Rough Endoplasmic Reticulum

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8
Q

What is the structure of RER?

A
  • a series of membrane, which enclose flattened sacs called cisternae
  • continuous with the nuclear membrane
  • Has ribosomes attached
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9
Q

What is the function of RER?

A

Synthesis and transport of proteins

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10
Q

What is the structure of smooth endoplasmic reticulum ?

A
  • a series of membrane, which enclose flattened sacs called cisternae, more tubular in appearance
  • No ribosomes attached
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11
Q

What is the function of smooth endoplasmic reticulum?

A

The synthesis and transportation of lipids

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12
Q

What is the structure of golgi body?

A

consists of flattened sacs of membrane called cisternae and hollow vesicles

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13
Q

What is the function of golgi body?

A
  • Chemically modifies proteins.
  • Produces lysosomes.
  • Produces glycoproteins.
  • Packages proteins for secretion out of the cell.
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14
Q

What is the structure of mitochondria?

A
  • Rod-shaped and 1-10 um in diameter
  • Double membrane separated by the fluid, inter membrane space
  • Inner membrane folded to form cristae
  • Matrix is the interior (contains enzymes)
  • contains DNA and ribosomes
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15
Q

Draw a mitochondrion diagram

A

(check in book)

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16
Q

What is the function of mitochondria?

A
  • site of aerobic respiration, synthesises ATP

- cristae increases surface area on which part of the respiratory process takes place

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17
Q

What are 2 extra facts about mitochondria?

A
  • cells with high metabolic activity contain many mitochondria (e.g. muscle cells)
  • the cylindrical shape gives a large SA:V and reduces diffusion distance (makes aerobic respiration more efficient)
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18
Q

What is the structure of chloroplast?

A
  • 2-10 um in diameter
  • Double membrane
  • Stroma (a fluid) makes up the interior, containing 70s ribosomes, lipids, circular DNA, starch granules and some products of photosynthesis
  • In addition there are thylakoids, forming stacks called granum (containing between 2-100 thylakoids), lamella forms in between
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19
Q

What is the function of chloroplasts?

A
  • site of photosynthesis (granum arrangement produces a large surface area, efficient for trapping light energy)
  • photosynthetic pigments such as chlorophyll found in thylakoids
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20
Q

What is the structure of vesicles?

A

Small membrane bound organelle

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21
Q

What is the function of vesicles?

A

Act as a contractile vacuole to maintain osmotic pressure

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22
Q

What is the the structure of vacuoles?

A

Large membrane bound organelle surrounded by a tonoplast

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23
Q

What is the function of vacuoles?

A

Storage of ions and organic molecules (e.g. proteins) and maintaining osmotic pressure

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24
Q

What is the structure of centrioles?

A

two hollow cylinders positioned at right angles to one another

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25
Q

What is the function of centrioles?

A

Are used in spindle formation (microtubles) in cell division.

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26
Q

What is the structure of lysosomes?

A

vesicles containing lytic enzymes

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27
Q

What is the function of lysosomes

A
  • responsible for destroying worn out organelles and for digesting the contents of vacuoles formed by phagocytosis
  • lysosomes isolate the potentially harmful enzymes from the rest of the cell
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28
Q

What is the structure of a cellulose cell wall?

A

Made of cellulose microfibrils in a polysaccharide matrix

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29
Q

What is the function of a cellulose cell wall?

A
  • prevents cell from bursting

- permeable to water

30
Q

What is the structure of plasmodesmata?

A

A narrow thread of cytoplasm that passes through the cell walls of adjacent plant cells

31
Q

What is the function of plasmodesmata?

A
  • Exchange of large organic materials via cytoplasmic streaming
  • Allows communication between adjacent cells
32
Q

What is the theory that describes the origin of chloroplasts and mitochondria?

A

Endosymbiotic theory

33
Q

What is the evidence for this theory?

A
  • 1883: division of chloroplasts was seen to closely resemble those of free living cyanobacteria
  • 1920s: mitochondria were once independent bacteria idea suggested
  • both have 70s ribosomes & circular DNA (could live independently)
34
Q

What does the theory mean?

A
  • That 1.5x10^9 ancient bacteria w/ fluid membrane engulfed other bacteria and developed a symbiotic relationship
  • Some bacteria could synthesise ATP from glucose and O2 and others could turn CO2 and water into glucose
35
Q

What does magnification mean?

A

the number of times an object is enlarged

36
Q

What does resolution mean?

A

the ability to distinguish between 2 points (refers to clarity of the image)

37
Q

Why are stains used?

A

Stains must be used to see structures clearer

38
Q

What is an advantage of electron microscopes?

A

Much higher resolution that light microscopes

39
Q

Describe the prokaryote cell structure (draw diagram)

A
  • Capsule: a mucilaginous layer of slime
  • Cell wall: Made of murein (also called peptidoglycan) -> amino acids and polysaccharides
  • Plasma Membrane
  • Mesosomes: infolding of cell membrane, site of respiration
  • Plasmid: small circular piece of DNA
  • Pilus: hair like protein extensions. Attachment and exchange of genetic material from one bacterium to another
  • Infolding of cell membrane: contain photosynthetic pigments. Site of photosynthesis (chromatophore)
  • 70s ribosomes: protein synthesis and free in the cytoplasm
  • Cytoplasm: jelly-like substance that contains enzymes and other soluble materials
  • Bacterial chromosomes: in an area called a nucleoid, not bound by histoproteins
  • Flagellum: sometimes more than one, rotates/waves for movement and lacks microtubules
40
Q

Describe generally prokaryotic cells

A

Cells contain no nucleus

Smaller ribosomes

No membrane-bound organelles

Generally less complex than the Eukaryotes

Peptidoglycan (murein) cell wall

Components float freely within the cytoplasm

41
Q

Describe generally eukaryotic cells

A

A cell whose major organelle’s are contained within membranes

Have a proper nucleus

Larger ribosomes than prokaryotic cells.

Usually have Mitochondria, Golgi Apparatus, Chloroplasts etc

Eukarotes include Animals, Plants and Fungi

42
Q

Compare Prokaryotes with Eukaryotes

A

No true nucleus / true nucleus
no membrane bound organelles / membrane bound organelles
0.1-10um / 10um to 10 cm
cell wall made of murein / cellulose of chitin
70s ribosomes / 80s ribosomes
circular DNA and plasmids / linear DNA in nucleus
no histone proteins / DNA associated with histone proteins
flagella / no flagella

43
Q

What is meant by tissue?

A

are groups or layers of similar cells working together to perform a specific function

44
Q

What is the definition for organ?

A

a collection of different tissues working together to perform a particular function

45
Q

Describe the structure of epithelial tissues

A
  • cells packed closely together (no gaps)
  • rest on the basement membrane
  • cells divide quickly
46
Q

Describe the function of epithelial tissues

A
  • covering and lining tissues
  • can also form glands
  • can secrete and absorb
  • can excrete waste products
47
Q

Describe the structure of squamous epithelial

A

thin and flattened cells

48
Q

What is the function of squamous epithelial tissue?

A
  • Lining tissue
  • used for diffusion (found where a thin diffusion path is needed)
  • found in alveoli, lining of blood vessels
49
Q

What is the structure of cuboidal epithelial tissue?

A

small cube shaped cells

50
Q

What is the function of cuboidal epithelial tissue?

A
  • involved with secretion and absorption

- e.g. lines the kidney tubules

51
Q

What is the structure of columnar epithelial tissue?

A
  • column shaped cells

- some have cilia and some have microvilli

52
Q

What is the function of columnar epithelial tissue?

A
  • secretion and absorption
  • Found in the trachea and bronchi with cilia.
  • Found in the small intestine with microvilli
53
Q

Describe the structure of glandular epithelial tissue?

A

Contain mucus secreting goblet cells

54
Q

What is the function of glandular epithelial tissue?

A

Secretion, e.g. mucus, enzymes, hormones

- line the digestive system: pancreas and salivary glands

55
Q

What are the general properties of muscle tissues?

A
  • contract to cause movement
  • inside the cells are protein fibres, which are made up of actin and myosin, they slide past each other to shorten the cell (contract)
56
Q

Describe the structure of connective tissue

A
  • except for blood, all the connective tissues contain the protein collagen in the extracellular material
  • between fibres are fat-storing adipocytes and immune system cells
  • found in the blood or bone, e.g. areolar connective tissues
57
Q

What is the function of connective tissue?

A

mostly bind organs or different types of tissues together, support and protect the body

58
Q

What is the structure of skeletal muscle?

A
  • muscle cells are joined together to form fibres (allow for powerful contraction, muscle tires)
  • striations caused = overlapping of protein molecules in cell
  • attached to bones by tendons
59
Q

What is the function of skeletal muscle?

A

VOLUNTARY MOVEMENT: skeletal movement, maintain posture and body position, support soft tissues

60
Q

What is the structure of smooth muscle?

A

unstriated, individual cells which can shorten in length

61
Q

What is the function of smooth muscle?

A

involuntary contraction, moves things around the body

- skin, walls of small intestine and blood vessels

62
Q

What is the structure of cardiac muscle?

A
  • striated and branched fibres
  • attached at their ends to adjoining fibres by thick plasma membranes, intercalated discs
  • no stimulation from nerves or hormones, although can modify contraction
63
Q

What is the function of cardiac muscle?

A

rhythmic contraction to pump blood through the HEART

64
Q

What is the definition of prokaryote?

A

a single-celled organism lacking membrane-bound organelles, such as a nucleus, with its DNA free in the cytoplasm

65
Q

What is the definition of eukaryote?

A

an organism containing cells that have membrane-bound organelles, with DNA in chromosomes within the nucleus

66
Q

What are the general properties of viruses?

A
  • Very small in size
  • Live in host cells
  • Use host cell to reproduce
  • Obligate parasites
  • Contain DNA or RNA
  • Wide variety
  • not a cell, no cytoplasm or organelles
67
Q

What is the basic structure of virus?

A
  • Nucleic acid core (RNA or DNA)
  • Protein coat (capsid)
  • Lipoprotein coat
    (second coat – only in enveloped viruses)
68
Q

What are the 2 types of viruses?

A
  • DNA viruses – stable, do not mutate rapidly
  • Single-stranded or double-stranded
  • Smallpox, Hepatitis B
  • RNA viruses – mutate rapidly, unstable
  • Single-stranded or double-stranded
  • Rhinovirus, Influenza, HIV
69
Q

What types of cell do viruses infect?

A
  • Viruses infect animal, plant and fungal cells

- Viruses can also attack bacteria. These are called bacteriophage

70
Q

What is chromatin?

A

Uncoiled DNA and associated proteins found in nucleus. DNA is in this form when the cell is not undergoing cell division

71
Q

State the 9 steps for protein production

A
  1. Nucleus contains DNA, codes for the amino acid sequences in proteins
  2. A mRNA copy of the DNA is made by transcription, small enough to fit through the nuclear pore into the cytoplasm
  3. The nucleus synthesises rRNA fro ribosome production
  4. Ribosomes synthesise the protein using the mRNA = translation
  5. RER transports protein
  6. Glogi body modifies protein (e.g. adding a prosthetic group) which is then packaged into a secretory vesicle
  7. Vesicle carrying the protein migrates towards the plasma membrane
  8. Vesicle fuses with the plasma membrane then the contents of the vesicle are emptied by exocytosis
  9. Mitochondria provide energy for the whole process

A-Level EDUQUAS Biology (24 decks)

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