2.1. 4-7 Cells Flashcards
1
Q
Name the 4 types of eukaroytic cells
A
- Plant
- Animals
- Fungal
- Protoctist
2
Q
What do all eukaroytic cells have?
A
- Nucleus surrounded by a nuclear envelope; containing DNA organised and wound into linear chromosomes
- Nucleolus is in the nucleus, contains RNA, where chromosomes unwind; the nucleolus is also involved in making ribosomes
- Jelly like cytoplasm in which organelles are suspended
- Plasma membrane (cell surface membrane)
- Membrane bound organelles
- Small vesicles
- Ribosomes
3
Q
What is the structure of a Nucleus?
A
- Surrounded by a double membrane called the nuclear envelope –> Contains pores.
- Nucleolus does NOT have a membrane around it. —> Contains RNA
- Chromatin is genetic material –> DNA wound around histone proteins —> when the cell is NOT dividing chromatin spread out or extend
- When cell is about to divide chromatin condenses and coils tightly into chromosomes.
These make up nearly all the organism’s genome
4
Q
What is the function of a Nucleus?
A
- Nuclear envelope separates the content of the nucleus and the rest of the cell
- Some regions, outer and inner nuclear membranes fuse together –> at these points some dissolved substances and ribosomes can pass through.
- Pores allow larger substances such as mRNA hormones to LEAVE the nucleus, some steroid hormones may ENTER the nucleus, from the cytoplasm via these pores.
- Ribosomes made in the Nucleolus
- Chromosomes contain the organism’s genes.
In Summery : the nucleus is the control center of the cell,
stores the organism’s genome,
transmits genetic information
provides the instructions for protein synthesis
5
Q
What is the structure for the ROUGH endoplasmic reticulum?
A
- System of membranes
- Contains fluid filled cavities called cisternae —> Continuous with the Nuclear membrane
- Coated with ribosomes.
6
Q
What is the function of the ROUGH endoplasmic reticulum?
A
- Intracellular transport system
- Cisternae forms channels for transporting substances from one area of the cell to another.
- Provides large surface area —> Ribosomes
- These proteins then actively pass through the membrane into the cisternae and are transported to the Golgi apparatus for modification and packaging
7
Q
What is the structure of the SMOOTH endoplasmic reticulum?
A
- System of membranes
- Contains fluid filled cavities called cisternae which are continuous with the nuclear envelope
- NO Ribsomes on the surface
8
Q
What is the function of the SMOOTH endoplasmic reticulum?
A
- Contains enzymes that catalyze reactions involved with lipid metabolisms such as:
- Synthesis of cholesterol
- Synthesis of lipids/ phopholipids needed by the cell
- Synthesis of steroid hormones - It is involved with absorption, synthesis and transport of lipids (from the gut)
9
Q
What is the structure of the Golgi apparatus?
A
- Stack of ‘MEMBRANE BOUND FLATTENED SACS’
2. Secretory vesicles bring materials to and from the Golgi Apparatus
10
Q
What are the functions of the Golgi Apparatus
A
- Proteins are modified
- Adding sugar molecules to make Glycoprotiens
- Adding lipid molecules to make Lipoprotiens
- Being folded into their 3D shape - Proteins packaged into vesicles, that are pinched off and
- Stored in the cell
- Moved to the plasma membrane, either to be incorporated into the plasma membrane
- Or to be exported out of the cell
11
Q
What is the structure of a Mitochondrion
A
- Spherical, rod-shaped, or branched and are 2-5um long
- Surrounded by two membranes with a fluid filled space between them —> Inner membrane highly folded into cristae
- Inner part of the mitochondrion is a fluid filled matrix
12
Q
What is the function of Mitochondrion
A
- Site of ATP production during aerobic respiration.
- They are self replicating —> If cell energy needs increase
- Abundant in cells where much metabolic activity takes place, for example:
- Liver Cells
- At synapses between neurons where neurotransmitter is synthesized and released
13
Q
What is the structure of chloroplast?
A
- Large organelles, 4-10 um long.
- Only found in Plants and some protoctists
- Surrounded by a double membrane or envelope —> Inner membrane is continuous with thylakoids (stacks of flattened membrane sacs) —> Which contain chlorophyll.
- Each stack of thylakoids = granum (grana = plural)
- Contains loops of DNA and starch grains.
14
Q
What is the function of chloroplast?
A
- Site of photosynthesis
- First Stage: Light energy trapped by chlorophyll and used to make ATP, occurs in the grana. —> Water split into Hydrogen Ions
- Second Stage: Hydrogen REDUCES CO2 using energy from ATP to make carbohydrates. Occurs in the Stroma
- Chloroplasts abundant in leaf cells, particularly palisade mesophyl layer
15
Q
What is the structure of a Vacuole?
A
The vacuole is surrounded by a membrane called the tonoplast and contains fluid
16
Q
What is the function of a Vacuole?
A
- Only plant cells have a large permanent vacuole
- Filled with water and solutes and maintains cell stability —> When full it pushes against the cell wall, making the cell turgid —> helps support the plant, especially non woody plants.
17
Q
What is the structure of Lysosomes
A
- Small bags, formed in the Golgi apparatus. —> Each surrounded by a double membrane
- Contain powerful hydrolytic (digestive) enzymes.
- Abundant in phagocytic cells such as neutrophils and macrophages.
18
Q
What is the function of Lysosomes
A
- Keeps the powerful hydrolytic enzymes separate from the rest of the cell
- Lysosomes can engulf old organelles and foreign matter —> digest them and return the digested components to the cell for reuse.
19
Q
What is the structure of a Cilia and undulipodia?
A
- Protrusions (extentions) from the cell and are surrounded by the cell surface membrane
- Each contains microtubules
- Formed from centrioles
20
Q
What is the Function of a Cilia and Undulipodia?
A
- Epithelial cells lining the airway contains 100s of cilia that beat and move the band of mucus
- Nearly all cell types have one cilium that acts as an antenna. —> Contains receptors and allows the cell to detect signals about its immediate environment
- The only type of human cell to have an undulipodium is a spermatozoon. (Allows it to move)
21
Q
What is the structure of a Ribsome
A
- Small spherical organelles. 20nm in diameter
- Made from ribosomal RNA
- Made in the nucleolus, as two separate sub units which pass through the nuclear envelope into the cell cytoplasm and then combine
- Some remain free in the cytoplasm and some attach to endoplasmic reticulum
22
Q
What is the function of the Ribsome
A
- Bound to the exterior of RER mainly for synthesizing proteins that will be exported outside of the cell
- Ones in cytoplasm either singly or in clusters are primarily the site of assembly of proteins used in the cell.
23
Q
What is the structure of a Centrioles?
A
- Consists of two bundles of microtubles at right angles to each other
- Made out of tubulin protein sub units
- Arranged to form a cylinder
24
Q
What is the function of a Centrioles
A
- Before cell divides, spindles (made of threads of tubulin), forms the centrioles
- Chromosomes attach to the middle part of the spindle —> Motor proteins walk along the tubulin threads, pulling the chromosomes to opposite ends of the cell
- Centrioles involved in the formation of cilia and undulipodia
- Before the cilia form, the centrioles multiply and line up beneath the cell surface membrane
- Microtubules then sprout outwards from each centriole, forming a cilium or undilipodium. - Usually absent from cells of plants but may be present in some unicellular green algae
25
What is the structure of a Cytoskeleton
1. Network of protein structures within the cytoplasm
2. Consists of
- Rod like micro filaments made of sub units of the protein actin. Polymers of actin and each micro filament is 7nm diameter
- Intermediate filaments about 10nm in diameter
- Straight, cylindrical micro tubules, made of protein sub units called tubulin
3. The cytoskeletal motor protien, myosins, kinesins, dyneins are molecular motors. ---> Also enzymes and have a site that binds to and allows hydrolysis of ATP as their energy source.
26
What is the function of a Cytoskeleton
1.Protein microfilaments within the cytoplasm give support and mechanical strength, keep the cells shape stable and allows cell movement
2. Microtubules also provide shape and support to cells, and help substance and organelles to move through the cytoplasm within a cell.
- Form Tracks along which motor proteins walk and drag organelles from one part of the cell to the other
3. Intermediate filaments: Anchor the nucleus within the cytoplasm
- Forms junctions, enables cell-cell signalling and allows cells to adhere to a basement membrane therefore stabilizing tissues
27
What is the structure of the Cellulose Cell wall
1. Made from bundles of cellulose fibres
28
What is the function of the Cellulose Cell Wall
1. Absent from animal cells
2. Prevents cell from bursting when turgid
3. Provides strength and support
4. Maintains cell's shape
3. Contributes to the support of the whole plant
4. Permeable, allow solutions to go through
Fungi have a cell wall made out of chitin not Cellulose
29
How is insulin (protein) made and secreted?
1. mRNA copy of the instructions (gene) for insulin is made in the nucleus
2. mRNA leaves the nucleus through a nuclear pore.
3. mRNA attaches to a ribosomes ---> reads instructions for assembly.
- Travel through the cisternae of the RER
4. Insulin molecules are pinched off in vesicles and travel towards Golgi apparatus
5. Vesicles fuse with Golgi apparatus
6. Golgi apparatus modifies and packages insulin molecules ready for release
7. Packaged Insulin molecules are pinched off in vesicles from Golgi apparatus and move towards plasma membrane
8. Vesicle fuse with plasma membrane
9. Plasma membrane opens to release insulin molecules outside.
30
What are the similarities between prokaryotic and eukaryotic cells?
Both have
- Plasma Membrane
- Cytoplasm
- Ribosomes
- DNA and RNA
31
What are the differences between prokaryotic and eukaryotic cells?
Eukaryotic cells are:
- Smaller
- Ribosomes smaller
- Less well developed cytoskeleton with NO centrioles
- No Nucleus
- No membrane bound organelles such as mitochondria, ER, chloroplast or Golgi
- Wall made from peptidoglycan not cellulose
- Naked DNA --- > Not wound around histone protiens ---> Loops not linear
32
What do prokaryotic cells also have?
1. Protective waxy capsule surrounding their cell wall
2. Small loops of DNA called plasmids
3. Main large loop of DNA
4. Flagella - long whip liked projections that enable them to move. ---> Flagella different from the Undulipodia of Eukaryotic cells
5. Pili - Small hair like projections that enable bacteria to adhere to host cells or each other.
- Allows passage of Plasmid DNA from one cell to another
33
What is meant by the endosymbiont theory?
The theory as to how eukaryotic cells arose from prokaryotic cells
34
How to prokaryotic cells divide
Binary Fission
