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Biology 1 > Cell structure and functions > Flashcards

Cell structure and functions Flashcards

1
Q

Parameters of a light microscope (LM)

A
  • Magnification (ratio size of image)
  • Resolution (Clarity of image measured by the minimum distance of 2 separate pouints we can see)
  • Contrast (Different in brightness between light and dark)
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2
Q

Organelle

A
  • Not visible in LM

- Membrane-enclosed structure within eukaryotic cell

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3
Q

Light microscope vs electron microscope

A

Light microscope:

  • Less resolution
  • Can view living things
  • Cannot see organelles that well

Electron microscope:

  • Reveals organelles
  • Much higher resolution
  • Cells must be dead during preparation
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4
Q

Characteristiques of all cells

A
  • Plasma membrane (membrane-bounded selective barrier)
  • Cytosol (semi-fluid
  • Chromosomes (carries genes in form of DNA)
  • Ribosomes (make protein)
  • Interior is cytoplasm
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5
Q

Difference between prokaryotic and eukaryotic cells

A
  1. Difference in location of DNA
    - Most eukaryotic cells: in nucleus which is bounded by a double membrane
    - Prokaryotes: in nucleoid region that is not membrane-enclosed
  2. Place of cytoplasm
    - Although all cells bounded by plasma membrane
    - Eukaryotic cells do not have cytoplasm in nucleus
  3. Organells
    - Eukaryotic cells: Have organelles suspended in cytosol in the cytoplasm
    - Prokaryotic cells: No organelles
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6
Q

What does the plasma membrane allow the passage of?

A
  • Oxygen
  • Nutrients
  • Waste for entire cell
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7
Q

Ratio of surface are to volume

A

IMPORTANT because there’s only a limited amount of substance that can cross second area of membrane

  • As size increases, the volume proportionately more than surface area
  • Smaller object has a greater ratio of surface area to volume –> this is why most cells are small
  • Cells exchanging material with surroundings may have projection (more surface area without adding volume)
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8
Q

Prokaryotic cells vs Eukaryotic cells

A

Prokaryotic:

  • Bacteria and archaea
  • Have cell membrane, ribosomes, DNA, cytoplasm
  • No organelles
  • DNA in nucleoid region

Eukaryotic:

  • Protists, fungi, animals, plants
  • Have cell membrane, ribosomes, DNA, cytoplasm
  • DNA in nucleus
  • Most membranes are phospholipid bilayers (different proteins embedded or on surface)
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9
Q

Components controlling genetics in eukaryotic cells

A
  1. Nucleus containing genetic information

2. Ribosomes making protein based on instructions from DNA

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10
Q

Elements in the nucleus

A
  • Nucleus (most genes)
  • Cytoplasts (some genes)
  • Mitochondria (some genes)
  • Enclosed by nuclear envelope which has a double membrane (there is space between the 2 membranes)
  • Nuclear envelope has pore
  • Nuclear lamina
  • Nuclear matrix
  • Chromosomes and chromatin
  • Nucleolus
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11
Q

Nuclear lamina

A
  • Net of protein filaments that lines the nuclear side of the envelope
  • For structural purposes
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12
Q

Nuclear matrix

A

Keeps the structure inside the nucleus

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13
Q

Chromosomes

A
  • Found in nucleus
  • Carry genetic information
  • Each is along DNA double helix with proteins
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14
Q

Chromatin

A

DNA with the associated protein

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15
Q

Nucleolus

A
  • Region inside a nucleus
  • Site of rRNA synthesis
  • Ribosomal subunit assembles
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16
Q

Endomembrane system in eukaryotic cell and how they are related

A
  • Nuclear envelope
  • Endoplasmic recticulum
  • Golgi apparatus
  • Lysosomes
  • Vesicles and vacuoles
  • Plasma membrane

Related by either:

  • Direct physical continuity
  • Transfer of membrane segments as tiny vesicles (sacs made of membrane)
17
Q

Endoplasmic reculum (ER)

A
  • Very extensive
  • Makes up more than 1/2 of total membrane in many cells
  • Consists of network of membranous tubules and sacs called cisternae
  • ER membrane is continuous with nuclear envelope
18
Q

Cisternae

A

Network of membranous tubules and sacs

19
Q

Two types of ER

A
  1. Smooth ER

2. Rough ER

20
Q

Smooth ER

A
  • Outer surface lacks ribosomes

Functions:

  • Synthesize lipids (oils, phopholipids, steroids)
  • Detoxidication of drugs
  • Storage of Ca2+
  • Metabolism of carbohydrate
21
Q

Rough ER

A
  • Outer surface is studded with ribosomes
  • Continuous with cytoplasmic side of nuclear envelope

Functions:

  • Many cells secrete proteins made by bound ribosomes on rough ER (ex. pancreatic cells make insulin on ER and secrete it in bloodstream)
  • Polypeptide chain enters lumen as it grows from ribosome
  • Enzymes in membrane add carbohydrates to proteins to make glycopoteins
  • ER membrane keeps secretory proteins separate from those that will stay in cytosol
  • Secretory proteins leave ER in transport vesicles that bud off from transitional ER
  • Membrane factory cell
22
Q

Glycoproteins

A
  • Carbohydrates added to proteins by enzymes made in the rough ER
23
Q

Ribosomes

A
  • Complexes made of rRNA and proteins
  • Carry out protein synthesis
  • Not-membrane-bounded (not organelle)

Two types:

  • Free ribosomes (suspended in the cytosol)
  • Bound ribosomes (attached to outside of ER or nuclear envelope)
24
Q

How does the mRNA help in protein synthesis?

A
  1. mRNA uses instructions from DNA
  2. mRNA exits nucleus for cytoplasm
  3. Ribosomes translate mRNA into a polypeptide
25
Q

Golgi apparatus

A

Functions:

  • Shipping and receiving centre
  • Transport vesicles often arrive here after leaving ER
  • Products of ER are modified, stored, sent to other places
  • Very extensive in cells that secret
  • Modifies products of ER (glycoproteins have carbohydrates modified; membrane phospholids may be altered)
  • Makes some macromolecules (polysaccharides)
  • Sorts and target products for different cell parts
  • Might add molecular tags to direct where the product should go (they’ll know where to “dock”)

Characteristics:
- Looks like many flattened cisternae

26
Q

Lysosomes

A
  • Membranous sac of hydrolytic enzymes that digest macromolecules (little bag of membrane)
  • Enzymes in lysosomes work best in acidic environments
  • Lysomal enzymes not very active in cytosol
  • Mostly in proteins
  • Digest in many circumstances
  • Recycle cell’s own organic material
27
Q

Lysosomal digestion

A
  • AMoebas and other unicellular eukaryotes feed by phagocytosis
  • The food vacuoles then formed fuses with lysosome for digestion
  • Macrophages in humans carry out phagocytosis
28
Q

Vacuoles

A
  • Large vesicles derived from ER and Golgi
  • Membrane is selective in transport of solutes
  • Solution in vacuole is different from cytosol

Functions:

  • Food vacuoles (formed by fagocytosis)
  • Contractile vacuoles pump out water cells
  • Central vacuole in mature plants develop as small vacuoles that fuse together, they contain sap

Biology 1 (11 decks)

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