Physiology Ex 1 - The Cell Flashcards Preview

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Flashcards in Physiology Ex 1 - The Cell Deck (22)
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What is the basic unit of life?

The cell


Define plasma membrane

The plasma membrane surrounds the cytoplasm of ling cells, physically separating the intracellular components from the intercellular components.


Define cytoplasm

The thick solution that fills each cell and surrounds its organelles


Define cytoskeleton

The intracellular matrix that supports cell shape and function


Define centrioles

A small set of microtubules arranged in a specific way. There are 9 groups of microtubules.


Nucleus and Nucleolus

The nucleolus is the nuclear subdomain that assembles ribosomal subunits in eukaryotic cells. The nuclear organizer regions of chromosomes, which contain the genes for pre ribosomal ribonucleic acid (rRNA) serve as the foundation for nucleolar structure


Define Endoplasmic Reticulum

ER is a network of membranous tubules within the cytoplasm of a eukaryotic cell, continuous with the nuclear membrane. It usually has ribosomes attached and is involved in protein and lipid synthesis


Define Gogli Apparatus

The Golgi is a complex of vesicles and folded membranes within the cytoplasm of most eukaryotic cells, involced in secretion and intracellular transport.


Define secretory vesicles

The secretory vesicle is a vesicle that mediates the vesicular transport of cargo - e.g. hormones or neurotransmitters - from an organelle to specific sites at the cell membrane, where it docks and fuses to release its content.


Define mitochondria

An organelle found in large numbers in most cells, in which the biochemical processes of respiration and energy production occur. It has a double membrane, the inner layer being folded inward to form layers (cristae)


Define Lysosomes

Organneles in the cytoplasm of eukaryotic cells containing degradative enzymes enclosed in a membrane.


Define Peroxisomes

Small, membrane-enclosed organelles that contain enzymes involved in a variety of metabolic reactions, including several aspects of energy metabolism such as catabolizing fatty acids


Define Proteasomes

Protein complexes inside all eukaryotes and archaea, and in some bacteria. In eukaryotes, they are located in the nucleus and the cytoplasm. The main function of the proteasome is to degrade unneeded or damaged proteins by proteolysis, a chemical reaction that breaks peptide bonds.


Label the cell components:


What is the cell composition? Percentage of cell mass of each of the following:

  • Water
  • Proteins
  • Carbohydrates
  • Lipids
  • Nucleic Acids
  • Ions

  • Water - 70-85%
  • Proteins - 10-20%
  • Carbohydrates - 1-3%
  • Lipids - 2%
  • Nucleic Acids - < 1%
  • Ions - < 1%


What is the composition of a phospholipid?

Polar head group linked to Glycerol backbone by Phosphate

2 Fatty acid chains




How is the phospholipid bilayer formed

From the mutual attraction of phospholipid tails surrounded by the aqueous milieu


What is the hydrophobicity of the phospholipid bilayer?

The surface is hydrophilic and the larger interior is hydrophobic


What influences membrane fluidity?

cholesterol and the degree of saturation of FA tails (1 is usually saturated and the other is not). Double bonds kink the molecule


How thick are cell membranes?

7.5 - 10 nm


What is the average composition of cell membranes?

  • 55% proteins
  • 25% phospholipids
  • 13% cholesterol
  • 4% other lipids
  • 3% carbohydrates

but composition varies with function, for example:

  • RBC - higher lipid
  • Myelin - higher lipid
  • Mitochondria - higher protein


What are two functions of membrane compartments that are necessary to carry out the physiological processes required for life?

  • Segregation of cellular compartments
  • Creation of electrochemical gradients