BPK 105 Study Guide - Midterm Guide: Active Transport, Facilitated Diffusion, Neuron

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Module 2: Cell Structures and their Functions - Study Guide
Specialized organelles within cells perform many functions that collectively provide the
cell with all the characteristics of life
main functions of a cell are to metabolize and use energy, communication, reproduction
of their genetic material and synthesize of molecules.
energy (ATP) used in cellular activities such as muscle contraction, synthesis of
molecules and transport of ions can be released from organic molecules (carbohydrates,
lipids and fats) during metabolism within the mitochondria and cytosol.
Each cell is surrounded by a cell membrane, separating the outside substances
(extracellular) from the inside of the cell (intracellular).
The phospholipids and proteins that make up the membrane create a selectively
permeable barrier that regulates what comes in and out of the cell.
Cell function requires that some substances be brought into the cell (nutrients for growth
and metabolism) and others removed (waste, synthesized substances for excretion).
Movement through the cell membrane can be passive (no energy required) with
substances moving freely through the membrane down their concentration gradient
(diffusion of O2, osmosis of water).
Charged ions and some larger molecules require very specific carrier mediated
mechanisms to move the phospholipid membrane.
Facilitated diffusion is a passive means of carrier mediated transport as substances
(glucose) move from high concentration to low concentration without the use of energy.
Primary active transport requires energy from ATP (sodium potassium pump).
Secondary active transport uses concentration gradient of one substance to drive the
movement of another (amino acids). The moment of larger substances may require the
fusion of a vesicle (bubble of membrane) with the cell membrane. When substances are
brought into the cell, membrane begins to form inward, surrounding the substance in a
vesicle during the process called endocytosis.
Substances manufactured in the cell often accumulate in vesicles near the surface,
when needed they are released through exocytosis, the vesicle fuses with the
membrane and releases its contents (enzymes, peptide hormones such as insulin).
Protein hormones (insulin) require membrane bound receptors to interact with the
hormone and send signals into the cell initiating movement through the membrane
(glucose) or a change in permeability (nerve signals from one nerve cell initiates the
movement of sodium into muscle initiating contraction).
Steroid type hormones are lipid soluble, and able to move through the cell membrane
into the nucleus to activate DNA.
The synthesis of proteins from DNA involves its transcription into messenger RNA
(mRNA) and its translation into a specific protein sequence.
The order of nucleic acids in a gene (portion of DNA) encode for the amino acid
sequence of the protein.These processes are collectively referred to as Gene
expression.
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Document Summary

Module 2: cell structures and their functions - study guide. Specialized organelles within cells perform many functions that collectively provide the cell with all the characteristics of life. Main functions of a cell are to metabolize and use energy, communication, reproduction of their genetic material and synthesize of molecules. Energy (atp) used in cellular activities such as muscle contraction, synthesis of molecules and transport of ions can be released from organic molecules (carbohydrates, lipids and fats) during metabolism within the mitochondria and cytosol. Each cell is surrounded by a cell membrane, separating the outside substances (extracellular) from the inside of the cell (intracellular). The phospholipids and proteins that make up the membrane create a selectively permeable barrier that regulates what comes in and out of the cell. Cell function requires that some substances be brought into the cell (nutrients for growth and metabolism) and others removed (waste, synthesized substances for excretion).

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