Flashcards in Cells and Tissues Deck (53):
What are the 7 differences between Eukaryotic Cells and Prokaryotic Cells?
E = large P = Small
E = Multi-cellular P = Uni-cellular
E = Always has a nucleus P = Never has a nucleus
E = Membrane - bound organelles P = No membrane-bound organelles
E = Linear DNA (associated with proteins) P = Circular DNA (not associated with proteins)
E = 80S Ribosomes P = 70S ribosomes
E = Has a cytoskeleton P = No cytoskeleton
What are the 3 similar properties between Eukaryotic and Prokaryotic cells (even though they have differences within these properties)?
1) Both have motility (E = Flexible, wavy undulipodium and P = Rigid, rotating flagellum)
2) Both can carry out cell division (E = Mitosis/Meiosis and P = Binary Fission)
3) Both can reproduce (E = Sexual or Asexual and P = always asexual)
Which cells are eukaryotes?
Which cells are prokaryotic?
What are the 10 organelles present in a eukaryotic cell?
4) 80S ribosomes
5) Endoplasmic Reticulum (70S and 80S)
6) Golgi body
What is contained within the cytosol/ cytoplasm?
5) Amino acids
What are the 4 parts of the nucleus?
1) Nuclear envelope = Double membrane
2) Nuclear pore = Large holes that contain the proteins, responsible for controlling the exit of substances outside of the nucleus
3) Nucleoplasm = Contains chromatin (DNA and proteins)
4) Nucleolus = Dark region of chromatin. Responsible for the synthesis of ribosomes
What is the role of mitochondria?
Site of aerobic respiration. Release energy (in the form of ATP from energy-rich molecules.
What is the role of ribosomes?
Site of protein synthesis.
Ribosomes that are free in the cytoplasm = synthesise proteins for cell's own use.
Ribosomes attached to the RER = synthesis proteins that will be exported out of the cell.
What is the common role that SER and RER have?
They are both MEMBRANE CHANNELS that:
1) Synthesise materials
2) Transport materials
What is RER function?
The ribosomes attached to it will synthesis the proteins that will be exported out of the cell.
The membrane channels will carry out post-translation modification on these proteins before it is exported out of the cell.
What is SER function?
To synthesise lipids for the cell's own use.
Where did the golgi body form from and what is its function?
The golgi body is a series of MEMBRANE VESICLES that form from the endoplasmic reticulum.
Its function is to transport the proteins synthesised by the ribosomes (attached to the RER) out of the cell.
Describe the process of how the golgi body transports proteins out of the cell?
1) The part of the RER that contains the proteins (synthesised by its ribosomes) ready to be exported out of the cell, will bind to one side of the golgi body.
2) On the other side of the golgi body, vesicles will bud off and fuse with the cell membrane.
3) Proteins are transported across the cell membrane via exocytosis
Where do lysosomes form from and what do they contain?
Lysosomes are small membrane-bound organelles formed from the RER.
Lysosomes contain digestive enzymes that will break down:
3) Whole cells
These materials will then be recycled.
What is the cytoskeleton and what is it's function?
A network of proteins fibres that extend throughout the cell. There function is to:
3) Mobility of cell
4) Shape of cell
5) Keep the organelles in position
What is the undulipodium and what is it's function?
It is an extension from the cell membrane. It is a flexible and wavy tail that contains motor proteins that allow it to carry out swimming movements.
What are the 2 types of undulipodium?
1) Flagellum (long)
2) Cilium (short and numberous)
What are microvili and what is their importance?
Finger-like extensions of the cell membrane. They are important for increasing the SA:V.
What 2 organelles do the prokaryotic cells that and in common with the eukarytotic?
2) Ribosomes (although: P = 70S)
What 4 organelles do the prokaryotic cells that eukarytotic cells don't have?
What is the nucleoid?
A region of cytoplasm containing DNA.
What are plasmids?
Seperate from the main form of DNA. They are used to transport DNA between different bacterial cells.
What is the capsule?
A thick polysaccaride layer around the cell wall. It enables bacterial cells to stick together in order to be protected from chemicals and phagocytosis.
What is the flagellum?
Rigid and rotating tail. The motor is driven by a H+ gradient across the cell membrane.
What is the role of the cell nucleus?
The nucleus contains DNA. DNA is a specific sequence of bases which code for genes. Genes will undergo protein synthesis. Proteins will have a specific shape which determines their function. Only certain genes will undergo protein synthesis - which determines the function of the cells.
What is the cell membrane?
A phospho-lipid bilayer
Why is the cell membrane described as a fluid-mosaic model?
Fluid - the components in the cell membrane can move around
Mosaic - the components all fit together
Describe the phospolipid bilayer:
It contains hydrophilic heads (polar) and hydrophobic tails (non-polar)
What are the 4 type of proteins in the cell membrane?
1) Transport Proteins (either by active transport or facilitated diffusion)
2) Enzymes (either catalyze reactions inside the cell or outside)
3) Receptor proteins (that have a specifically-shaped binding site - if activated, the receptors will cause a reaction in the cell membrane or cell cytoplasm)
4) Recognition proteins = GLYCOPROTEINS
What are the 4 types of transport that occurs across a cell membrane?
1) Lipid diffusion
2) Facilitated diffusion
4) Active Transport
Describe Lipid diffusion:
The transport of hydrophobic molecules and small hydrophilic molecules directly across the membrane
Describe facilitated diffusion:
The transport of hydrophilic molecules either via a:
1) Carrier intrinsic protein: That has a specific binding site. In high concentrations of a specific molecule. The molecule will bind and cause the protein to change shape. The molecule is released to low concentrations. Co-transport.
2) Channel proteins: (stimulus)-gated channels. When in the presence of a certain ion they will change their permeability.
The movement of water from an area of high water potential to an area of low water potential (across a semi-permeable membrane).
Describe active transport:
Requires ATP. Occurs across a carrier protein.
What are the 4 basic tissues:
Where is epithelial tissue located?
Underlying most internal and external surfaces of the body.
What are the 5 functions of epithelial tissue?
1) Protects underlying layers
2) Exchanges chemicals with underlying layers
3) Detects stimuli
4) If cells are closely packed together can form 1) Endocrine or 2) Exocrine glands - secrete hormones
5) Can form glands that secrete sweat and mucus
Why is the word 'Avascular' used to describe epithelial tissue?
As underlying tissues receive nourishment from the epithelial tissue.
What are the 3 basic morphologies of epithelial cells?
1) Squamous (flat and wide)
2) Cuboidal (approx. same width and height)
3) Columner (thin and tall)
The arrangement of the epithelial cells depends on their function:
Simple - absorption/secretion
Stratified - protection
Transitional - expansion
What are the 3 components of connective tissue:
2) Fibers (reticular/collagen/elastin)
What is homoeostasis and why is it important?
It is the condition whereby the body's internal environment is maintained at a relatively constant level (within restricted set points).
It is important so the cells survive and function efficiently.
What 3 things are required for homeostatis to occur?
1) (mainly) negative feedback mechanisms.
2) Physiologcial control mechanisms
3) Sensory receptors
What is a variable?
A change in the internal environment.
What is the set point?
The point at which a variable should aim to be maintained at in order for the cells to survive and function efficiently.
What is the difference between fluctuations that occur in the internal and external environment?
Internal - small fluctuations
External - large fluctuations
Give 5 examples of set points:
Blood glucose (4.5 - 5.6 mmol/L)
Oxygen (75- 100 mmHg)
CO2 (36 - 46 mmHg)
BP (80 - 120 mmHg)
What carries out negative and positive feedback mechanisms?
PHYSIOLOGICAL CONTROL MECHANISMS
Will a variable always be maintained at its set point?
No - it will always oscillate about its set point. The less oscillations the more effective the physiological control mechanism in carrying out the feedback mechanism
What are 2 differences between negative and positive feedback mechanisms?
1) Negative occur more often and positive occur rarely (they normally occur when the physiological control mechanisms that carry out the negative mechanisms have broken down)
2) Negative mechanisms will return the variable to set point and positive will enhances the effects of the change in variable in the same direction.
Give 2 examples of a variable controlled by a -ve feedback mechanism:
1) Core body temperature control
2) Regulation of blood pressure