Flashcards in Chapter 2 - Cellular Activity Deck (42):
What is the Nucleus?
It contains most of the cell's DNA.
What is Nucleolus?
It is made up mainly of RNA.
What is a Cytoplasm?
It is the fluid in which the organelles of the cell are suspended.
What is the Golgi Apparatus?
It modifies and packages proteins for secretion from the cell.
What is the Endplasmic Reticulum?
It is the membranous channels that store and transport materials; it also provides a surface on which chemical reactions occurs.
What are Ribosomes?
They are the sites of protein synthesis.
What is the cell membrane?
It separates the cell contents from the surroundings.
What is the Mitochondria?
It is the site of the reactions of aerobic respiration.
What is the Cytoskeleton?
It is a framework of microfilaments and tubules that support the cell.
What are the nuclear pores?
They are the openings in the nuclear membrane through which large molecules can pass.
Why is the membrane called a Fluid Mosaic Model?
The membrane is said to be a fluid because the molecules if which it is made are constantly changing position and it is said to be mosaic because it is composed of many different kind of molecules.
Explain the structure of the cell membrane.
The membrane is composed of phospholipid molecules which contain a phosphate group; they are arranged in a bilayer. Each phospholipid molecule has a head that is hydrophilic, (water loving) and a tail that is hydrophobic (water hating). Heads outside and tails inside.
What are Channel proteins?
They are proteins that allow the transport of specific substances across the cell membrane.
What molecules are embedded in the phospholipid bilayer?
Protein molecules and cholesterol molecules.
What are functions of the cell membrane?
•A Physical Barrier
•The regulations of the passage of materials
How does the Sensitivity of the cell membrane work?
The cell membrane is the first part of the cell affected by any changes in the extracellular fluid. It also has receptors that are sensitive to particular molecules in its immediate environment.
How does the cell membrane act as a Support?
The internal part of the cell membrane is attached to microfilaments of the cell's cytoskeleton, thus giving support to the whole cell. There are also connections between the membranes of adjacent cells which give support to the whole tissue of which the cells are a part.
What do membrane proteins include?
List all Membrane Transportation.
-> Carrier Mediated Transport
• Facilitated Diffusion
• Active Transport
List the important characteristics of Carrier Mediated Transport.
•Specific; only bind to a particular molecule.
•When saturated; cannot increase the rate of movement.
•Carrier activity is regulated by substances like hormones.
What substances are transported through Diffusion?
Water, Oxygen. Carbon Dioxide. Alcohol, Fatty Acids, Steroids; ions such as sodium, potassium, calcium; lipid soluble drugs.
What substance is transported through Osmosis?
What substances are transported through Facilitated Diffusion?
Glucose and Amino Acids.
What substances are transported through Active Transport?
Certain ions, glucose ad amino acids.
What substances are transported through vesicular transport?
Cholesterol, iron ions.
Micro-organisms and cell debris but only by certain specialized cells.
Secretions like mucus or digestive juices.
Describe Receptor Proteins.
Receptor Proteins are sensitive to certain molecules outside the cell. They are specific; lock and key analogy can be used.
Why is there a variation in the sensitivities of cells to hormones?
Because different cells have different types and numbers of receptor proteins.
How do Nerve Cells communicate?
One nerve cell releases a substance (a neurotransmitter) that is detected by the receptor proteins of an adjacent cell, which in turn responds by producing nerve impulses.
What is the main role of genes?
They determine the proteins that a cell can make.
What does Nucleotide consist of?
Ribose (a 5-carbon sugar), a phosphate group and a nitrogenous base, a base that contains nitrogen atoms.
What does protein synthesis involve?
It involves the code for the protein being taken from the DNA in the uncles out into the cytoplasm. Ribosomes, then read the code and join the amino acids together in the order specified by the code.
What happens if the proteins made during protein synthesis are to be secreted from the cell?
They are packages into vesicles by the Golgi Apparatus.
How are amino acids joined in a protein?
By chemical bonds called peptide bonds.
List the functions of proteins.
•Transport across membranes
How does protein provide structure?
•Keratin - provides strength
Eg. hair, nails and skin.
•Collagen - provides strength and flexibility.
Eg. Tissues like bone, cartilage and deep layers of the skin.
How does protein provide transport across membranes?
Some proteins form channels in membranes while others act as carriers to transport materials across the membrane.
How does protein provide Communication?
Many hormones are proteins. Secretes into the extracellular fluid they stimulate other proteins, which act as receptors in the membranes of cells.
How does protein provide Cell Metabolism?
Enzymes are proteins and they are present in a cell to determine the chemical reactions that take place within a cell.
How does protein provide Recognition?
Proteins in the cell membrane are unique to a particular person. The immune system doesn't attack the body's own cells but foreign proteins will stimulate the production of antibodies.
How does protein provide Movement?
Protein molecules are able to change shape and this is the basis for the movement of structures within the cell or movement of the whole cell like a muscle cell.
What is an organelle?
Any membrane-bound structure found inside a cell.
Eg nucleus, ribosome, etc.