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Cell and Molecular Bio > Cell and Molecular Bio- Intro to Cell theory and Membranes > Flashcards

Cell and Molecular Bio- Intro to Cell theory and Membranes Flashcards

1
Q

Organisms may be of two types:
Unicellular
Multicellular
Define these terms:

A

Unicellular-any life for that consists of just a single cell
Multicellular-organisms that consists of more than 1 cell

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2
Q

There are two types of cells
Eukaryotes
Prokaryotes

Define and give examples of these:

A

Prokaryotes-cells with no membrane bound organelles (nucleus)
Bacteria
Archaea

Eukaryotes-cells with membrane bound organelles, more complex structure (has nucleus).
Animal cell 
Plant cell 
Fungal cell 
Protist cell
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3
Q

What is the function of the nucleus?

A
  • control center
  • contains DNA (genetic material that code hereditary information and controls the cell’s growth and reproduction)
  • largest organelle
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4
Q

Cell size:

A
  • smaller cells have larger amount of surface area compared to volume
  • An increase in surface area allows for more nutrients to pass into the cell and waste to exit the cell
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5
Q

What are the 5 components of the nucleus?

A
  1. Nuclear envelope
  2. Nuclear pore
  3. Nucleolus
  4. Chromatin
  5. Nucleoplasm
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6
Q

What is function of the Nuclear envelope?

A

Prevent the substances from moving freely into and out of a nucleus

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7
Q

What is function of the Nucleolus?

A
  • spherical dense mass of material

- Site for the synthesis of ribosomal RNA and for the formation of ribosomal sub units

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8
Q

What is function of the Nuclear Pores?

A

Permit the selective transport of substances across the nuclear envelope.

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9
Q

What is function of the Chromatin?

A

Diffuse DNA (DNA compacts into chromosomes before cell division)

The primary function is to package long DNA molecules into more compact, denser structures

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10
Q

What is function of the Nucleoplasm (nuclear plasm)?

A
  • nucleus sap, similar to the cytoplasm

- Maintains the structure

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11
Q

Describe the structure of the cell membrane:

A
  • composed of a double layer of phospholipids (phospholipid bilayer) and proteins
  • Flexible boundary between a cell and its environment
  • Controls what enters or leaves the cell
  • Selectively permeable-some substances pass freely, some transported, some prohibited
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12
Q

Semi-permeability of cell membrane:

A

Impermeable to:
large and polar molecules such as ions, proteins and polysaccharides

Permeable to:
non polar and hydrophobic molecules like lipids as well as to small molecules like O2, CO2, N2

Permeability: depends on solubility, charge, chemistry and solute size

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13
Q

Why are cell membranes selectively permeable?

A

> Essential molecules enter
Metabolic intermediates remain
Waste products exit

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14
Q

What is the role of Cytoplasm?

A
  • In eukaryotic cells, includes all of the material inside the cell and outside the nucleus.
  • contains organelles to carry out specific jobs
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15
Q

What is Cytosol?

A

jelly like substance of cytoplasm where the other parts of the cytoplasm such as various organelles and particles remain suspended

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16
Q

What is the function of Ribosome?

A

protein factory

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17
Q

Explain the process of how ribosomes are made:

A
  1. Built in nucleolus-> 2. shipped out of nucleolus -> 3. through nuclear pores -> 4. to cytoplasm in eukaryotic cells
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18
Q

Characteristics of Ribosomes:

A
  • exists in eukaryotes and prokaryotes
  • Non-membrane bound structure
  • Numerous non-soluble particles in the cytoplasm of cells either free or attached to the endoplasmic reticulum
  • contain RNA and protein-> the site of manufacturing proteins
19
Q

What is the function of cytoskeleton?

Name the 3 types of cytoskeletons:

A

help maintain a cell’s shape and either anchors the organelles or assists in their movement

  1. Microtubules
  2. Actin filaments
  3. Intermediate filaments
20
Q

Characteristic of cytoskeleton:

A

A network of filaments or fibres that is present in the cytoplasm of eukaryotic cell.

21
Q

Characteristic of the Endoplasmic reticulum:

A
  • network of membranes
  • attached to the nuclear membrane
  • 2 forms:
  • smooth
  • rough (they are usually interconnected)
22
Q

Characteristic and role of the Rough Endoplasmic Reticulum (RER):

A
  • Has ribosomes attached to the outer surface
  • Makes proteins
  • Also has enzymes that can add glucose to protein= glycoproteins (exported by the cell)
23
Q

Characteristic and role of the Rough Endoplasmic Reticulum (RER):

A
  • No attached ribosomes

- RER and SER are interconnected

24
Q

Characteristic and role of the Golgi Apparatus:

A

(postmen)

  • stacks of flattened membrane-bound sacs
  • receives, modify and packages proteins or lipids from ER to export from cells
  • packed with enzymes that complete the processing of modifying proteins
25
Q

How does the Golgi Apparatus modify proteins?

A
  • Add sulphur or phosphorus atoms to certain regions of the protein
  • Cut off tiny pieces of the protein ends
26
Q

Describe the structure and function of a Lysosome:

A

structure: small spherical organelles enclosed by a single membrane (common in animal cells, rare in plant cells)
- synthesized in the RER and matured in the Golgi Apparatus

function: contains powerful digestive enzymes that break down worn out organelles and ship their building blocks to the cytoplasm where they are used to construct new organelles
- also dismantle and recycle proteins, lipids and other molecules

27
Q

Describe the function and role of Peroxisomes:

A

structure: contain oxidative enzymes
- resemble lysosome but DO NOT develop through Golgi A

function: protective function, oxidation of biomolecules
e. g found in liver cells contain the enzyme catalase which neutralizes dangerous peroxides such as H2O2

28
Q

Describe the structure and role of Mitochondria:

A

structure: bound by double membrane
- outer membrane: faces the cytoplasm
- inner membrane: folds into projections called cristae
- Has their own DNA (mtDNA), genes code for enzymes proteins and other essential
- Has their own ribosomes (similar to bacteria ribosomes)

function:

  • make energy via cellular respiration
  • takes in nutrients from the cell, breaks it down and turns into energy
29
Q

What is cellular respiration?

A

The process of oxidizing food molecules e.g glucose using O2 and giving off CO2 & H2O
The energy released is captured in the form of ATP for use by all energy-consuming activities of the cell

30
Q

Fluid mosaic model:

A

Membrane is considered a mosaic of lipid, protein and carbohydrate molecules

membrane exhibits properties that resemble a fluid because lipids and proteins can move relative to each other within the membrane

31
Q

Plasma membrane:

A

also a phospholipid bilayer which is essentially a membrane that can cover a cell or a cell organelle

32
Q

Explain the function of the cell membrane?

A

1-Separate internal cellular environment from external environment
-very thing

  1. All cells must take in and release substances to survive, grow and reproduce
  2. Controls movement of materials into and out of the cell
    - Allow certain molecules to cross freely -> selective permeability
33
Q

What are the 4 components of the cell membrane?

A
  1. Phospholipids
  2. Cholesterol
  3. Membrane proteins
  4. Membrane carbohydrates
34
Q

What are Phospholipids?

A

A class of amphipathic molecules. Possessing both hydrophilic (water loving, polar) and lipophilic (fat loving, non polar, hydrophobic) properties.

35
Q

What is the role of cholesterol in the cell membrane?

A

-Important for membrane fluidity and integrity
In warm temp: cholesterol molecules interfere with phospholipid movement and reduce membrane fluidity

In cool temp: cholesterol keeps the saturated fatty acid tails from packing and maintains adequate fluidity. Prevent it from being too rigid.

36
Q

Structure and characteristics of cholesterol in the cell membrane:

A

Amphipathic molecule
>Hydrophilic: hydroxyl (OH) group aligns with the phosphate heads of phospholipids.

> Hydrophobic: remaining portion which tucks itself into fatty acid portion of the membrane

37
Q

What are the two classes of membrane proteins?

A
  1. Peripheral membrane proteins: adhere only temporarily to the cell membrane with which they are associated with
    - attach to integral proteins, or
    - penetrate the peripheral regions of the lipid bilayer
  2. Integral Proteins: penetrate lipid bilayer across the whole membrane (transmembrane protein)
38
Q

What are the 6 major membrane protein functions?

A
  1. Transport
  2. Enzyme activity
  3. Signal transduction
  4. Attachment to cytoskeleton and extracellular matrix
  5. Cell to cell recognition
  6. Intracellular joining
39
Q

Characteristics of membrane carbohydrates:

A

(5-8%) of the cell membrane
The extracellular surface of the cell membrane is decorated with carbohydrate groups attached to lipids and proteins, this occurs through glycosylation.

40
Q

Glycolipids and Glycoproteins

A

Glycogen and lipids

Glycogen and proteins

41
Q

What are the functions of membrane carbohydrates?

A
  • cell recognition e.g A,B,O blood typing

- cell adhesion e.g cell-cell signaling or cell pathogen interactions

42
Q

More details on the 6 major functions of membrane proteins:

A
  1. Transport: A protein that spans a membrane may provide a hydrophilic channel across the membrane that is selective for a particular solute
    - other proteins may shuttle a substance from one side to the other by changing shape. Hydrolyze ATP as an energy source to actively pump substances across the membrane
  2. Enzyme Activity: Carries out sequential steps of a metabolic pathway. Protein with active site exposed to substances.
  3. Signal transduction: Membrane protein with binding site with a specific shape that fits the shape of a chemical messenger (hormone).
    The external messenger (signal) may cause a change in the protein (receptor) that relays the message to the inside of the cell
  4. Cell-cell recognition: Some glyco-proteins serve as identification tags that are specifically recognized by other cells
  5. Intercellular joining: Membrane proteins of adjacent cells may hook together in various kinds of junctions, such as gap junctions or tight junctions
  6. Attachment to the cytoskeleton and extracellular matrix:
    Microfilaments or cytoskeleton may be bonded to membrane proteins, a function that helps maintain cell shape and stabilizes the location of certain membrane proteins. Proteins that adhere to the ECM can coordinate extracellular and intercellular changes
43
Q

What are the two types of transport in the membrane?

A
  1. Active
    - bulk transport
    - pumps
  2. Passive
    - facilitated diffusion
    - osmosis
    - diffusion
44
Q

Define Osmosis:

A

The net movement of water particles from a high water potential to low water potential through a semi-permeable membrane

Cell and Molecular Bio (13 decks)

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