Chapter 1: Cells Review Flashcards
What is homeostasis?
Homeostasis is the process in which a cell or organism maintains its internal environment at equilibrium even though the external environment changes.
Why is the Surface Area to Volume ratio important?
The cell needs enough surface area to supply material or remove wastes from the metabolically active cytoplasm.
What is the surface area equation?
6L^2
What is the volume equation of a cell?
L^3
The internal volumes …? at a greater rate than the surface area of their plasma membrane
increase
What happens beyond a given cell size?
The two way exchange of materials cannot occur fast enough to sustain the cell.
What are prokaryotic cells?
They are simple cells that lack a nucleus and membrane bound organelles.
What kingdoms do prokaryotic cells belong to?
Bacteria
What are eukaryotic cells?
Complex cells that contain a nuclear envelope or membrane and also contains membrane bound organelles.
What kingdoms do eukaryotic cells belong to?
Animal, plants, fungi and protists.
Similarities between prokaryotes and eukaryotes.
Contain genetic information have plasma membranes CHONP Produce proteins Use ATP
Distinguish differences between prokaryotes and eukaryotes.
Prokaryotes: . No membrane bound organelles . No nucleus . Simple . Unicellular . Smaller Eukaryotes: . Membrane bound organelles . Nucleus . Complex . Larger . Majority multicellular
What is the width of the plasma membrane?
4-10nm
What is the plasma membrane?
An active boundary that separates the internal environment from the surroundings and can exclude the entry of substances, permitting entry of some and eliminating others.
What does semi-permeable mean?
Allows only some substances to cross in and out.
What are the two major components of the plasma membrane?
. Phospholipids- The main structural component
. Proteins- embedded in the membrane
The plasma membrane consists of …? of phospholipids?
. Double Layer (Bi layer)
What can the phosphate head be described as?
Hydrophilic, polar
What can the fatty acid tails be described as?
Hydrophobic, non-polar
What is hydrophobic?
Water fearing
What id hydrophilic?
Water loving
Why do the hydrophobic tails face each other?
Because the water repels the fatty acid tails. Water and oils do not mix.
What state are fatty acids at body temperature?
Liquid
Define viscous
Having a thick, sticky consistency between solid and liquid
What can proteins be grouped into in the cell membrane?…………./……….
. Integral proteins: - Adhesion - Receptor - Enzymatic - Transport . Peripheral proteins
What are integral proteins?
Fundamental components of the membrane. They are embedded in the phospholipid membrane and typically span the width of the membrane. (trans-membrane).
What are glycoproteins?
Carbohydrate groups, such as sugars, are attached to the exposed part of the proteins on the outer side.
What are peripheral proteins?
Proteins anchored to the exterior of the plasma membrane through bonding with lipids or are indirectly associated with the plasma membrane with interactions with integral proteins.
Why is “fluid” used to describe the cell membrane?
Because the fatty chains of the phospholipids are viscous or like a thick oily liquid.
Why can the cell membrane be described as “mosaic”?
The external surface has the appearance of a mosaic as because of the various embedded proteins set in a uniform background.
What are the functions of the plasma membrane?
- An active and selective boundary
- Denotes cell identity
- Receives external signals
- Transports materials
What is the cell theory?
- All organisms are composed of cells.
- Cells are the smallest living things.
- Cells all arise from pre-existing cells.
Which organelles are membrane bound?
. Nucleus
. Smooth and Rough endoplasmic reticulum
. the Golgi apparatus
. lysosomes
Which organelles have an internal and external membrane?
. Mitochondria
. Chloroplasts
Are ribosomes membrane bound?
No
What is the function of the nucleus and where is it found?
It is found central in animal cells and next to the large vacuole in plant cells in the cytosol. It contains the nucleolus and contains genetic information for cell function and protein synthesis.
What is the function of mitochondria and where are they found?
Mitochondria are responsible for the generation of energy for the cell’s use through cellular respiration and is found freely in the cytosol.
What is the function of ribosomes and where are they found?
The ribosomes are composed of proteins and rRNA and synthesises proteins from and mRNA transcript, by the process of translation. It is dispersed in the cytosol or attached to the endoplasmic reticulum.
What would happen to the phospholipids if it was cold and there was no cholesterol?
. Phospholipids cluster together
. Less Movement
. Less Energy
. Too rigid and might break
How does the cholesterol help the cell membrane in cold climates?
Acts as a buffer and regulates fluidity by interrupting bonds between tails, therefore loosening the membrane.
What would happen if the phospholipids were in a hot climate without cholesterol?
. Phospholipids spread out . More movement . More energy . Too fluid . Can't hold its shape
How does cholesterol help the cell membrane in hot climates?
Acts as a buffer and regulates fluidity be interrupting bonds between tails, therefore reducing movement.
What is the process of glycocalyx?
the process of the cell denouncing cell identity through glycoproteins or glycolipids.
What does saturated mean?
Single bonds only (max no. of hydrogens)