C3 Cell Structure Flashcards
(47 cards)
1
Q
Eukaryotes
A
These are (mostly) multicellular organisms made up of eukaryotic cells like animals, plants, fungi, and protists.
2
Q
Prokaryotes
A
These are single-celled organisms made up of prokaryotic cells like bacteria.
3
Q
Organelles found in a typical animal cell
A
- Cell Membrane
- Nucleus
- Mitochondria
- Endoplasmic Rectilium(smooth and rough)
- Golgi Apparatus
- Lysosome
- Ribosome
4
Q
Nucleus Structure
A
Controlling the cell’s activities - The DNA contains instructions to produce proteins
1. Nuclear Envelope - Double membrane; outer membrane has ribosomes on its surface; controls entry and exit of substances out of the nucleus
2. Nuclear Pores - allows the passage of larger molecules
3. Nucleoplasm - makes up bulk of nucleus (the inside)
4. Chromatin, which is the form chromosomes take when not dividing, and these contain DNA - protein bound, linear DNA
5. Nucleolus - spherical region within the nucleus, makes ribosomal DNA and assembles them (can be more than one)
5
Q
Cell Membrane
A
Found on the surface of animal cells - controls what enters and leaves the cell.
Fluid - phospholipids can move
Cell signalling - Receptors can detect signals from other cells
Phospholipid Bilayer
6
Q
Cell Wall Properties
A
- Supports the cell - The contents of the cell press against the cell wall to make it rigid.
- Prevents the cell from bursting - The cell wall can withstand high osmotic pressure.
- Allows exchange of substances between cells.
- Made up of cellulose.
- Contains channels (gaps) known as plasmodesmata (or plasmodesma if just one).
7
Q
Mitochondria
A
- Site of aerobic respiration
- Has a double membrane, and the inner membrane is folded to make extensions called cristae which provides a large surface area for enzymes and proteins involved in respiration to attach to.
- The matrix makes up the remainder of the mitochondrion, which contains ribosomes and DNA, allowing the mitochondria to manufacture their own proteins. Many enzymes used in respiration are also found in the matrix.
8
Q
Ribosomes
A
- Site of protein synthesis
- Involved in the process of translation
- Two sizes: 80s (eukaryotic) 70s (prokaryotic + smaller)
- Made of two sub units, one large and one small.
9
Q
Golgi Apparatus
A
- Stack of membranes that make up flattened sacs (cisternae) with hollow structures.
- Proteins are passed through it to be modified and added to other molecules.
- It labels proteins to be transported to their correct destination
- (the modified proteins are transported in Golgi Vesicles to the cell surface to fuse with the membrane to release contents to the outside).
- Stores lipids and proteins
10
Q
Lysosomes
A
- Lysosomes are vesicles produced by the Golgi apparatus that contain hydrolytic enzymes.
- They digest worn-out organelles so useful chemicals can be reused.
- They breaks down dead cells (autolysis).
- They can also be released to the outside of the cell (exocytosis) to destroy material around the cell
11
Q
Endoplasmic Reticulum
A
- They contain a system of membranes enclosing a fluid-filled space, known as cisternae.
- R(rough)ER
1. Provide large surface area for the synthesis of proteins and glycoproteins [the proteins are made using the ribosomes (that are on the outer surface of the cisternae)]
2. Provides a pathway for materials throughout the
cell i.e. proteins - S(smooth)ES
1. Synthesis, storage, and transport of lipids and carbohydrates.
12
Q
Chloroplasts
A
Site of photosynthesis - These reactions take place in the grana and stroma.
- Thylakoid - fluid-filled sacs that contain chlorophyll; where 1st stage of photosynthesis takes place.
- Grana - 100 thylakoid; ech thylakoid contins chlorophyll
- Stroma - fluid-like matrix where the 2nd stage of photosynthesis takes place.
- They have a double membrane
13
Q
Vacuole
A
- They help maintain pressure within the cell, which keeps the cell rigid and stops the plant from wilting.
- Tonoplast - the name of the membrane surrounding the organelle
- Contains cell sap (a solution of salt and sugars).
14
Q
Algae
A
- Contain the same organelles as plant cells.
- Contain chloroplasts with different shapes to those found in plant cells.
- The cell wall is made of cellulose and/or glycoprotein
15
Q
Fungi
A
Contain most of the organelles found in plant cells.
- Do not contain chloroplasts.
- Cell walls are made up of chitin rather than cellulose.
16
Q
Specialised cells
A
These are cells with certain features that allow them to carry out a particular function.
17
Q
Tissue
A
This is a group of similar cells working together to carry out a particular function.
18
Q
Organ
A
This is a group of tissues working together to carry out a particular function.
19
Q
Organ system
A
This is a group of organs working together to carry out a particular function.
20
Q
Examples of animal tissues
A
- SQUAMOUS Epithelial tissue - sheets of cells that line organs and have protective functions.
- CILIATED epithelium - lines organs such as the trachea where it can sweep mucus away from the lungs; made up of ciliated epithelial cells and goblet cells. The goblet cells release mucus to trap pathogens, whilst the ciliated epithelial cells use cilia to sweep the mucus away.
21
Q
Examples of plant tissues
A
- Xylem - transports water, and mineral ions through the plant; made up of dead xylem vessel cells which have no end walls and no organelles.
- This forms a continuous column through which water can flow.
- The walls of these cells are strengthened by a waterproof material known as lignin.
22
Q
Prokaryotic Cell Structure
A
- SLIME CAPSULE - protects bacterial cells from other cells & helps bacteria stick together for protection.
- PILI - used for attaching to other cells or surfaces.
- FLAGELLA - assist the cell in movement.
- PLASMID - extra genes tp aid in survival (eg for antibiotic resistance) found in smaller loops.
- MUREIN - makes up cell wall
23
Q
Comparing prokaryotes and eukaryotes
A
- P: no nucleus E; contains nucleus
- P: circular DNA free in cytoplasm E; DNA enclosed in nucleus, linear
- P: DNA bound to proteins E; DNA not associated w/ histones/proteins
- P: no membrane-bound organelles E; contains membrane-bound organelles
- P: ribosomes size 70s E; ribosomes 80s
- P: MUREIN cell wall E; plants have cellulose, fungi have chitin cell wall
24
Q
What do Prokaryotes, Mitochondria and Chloroplasts have in common?
What does this suggest?
A
- 2 circular strands of DNA
- 70S ribosomes
- Mitochondria may have evolved from prokaryotes
or - Eukaryotes may have engulfed a prokaryote forming an endosymbiotic relationship and evolving into mitochondria
25
Virus Structure
- Always present:
1. Genetic material - Viral genomes may be DNA or RNA and single or double-stranded.
2. Capsid - A layer of protein molecules that surrounds and protects the genetic material.
- Sometimes present:
1. Lipid Envelope - An outer layer made up of phospholipids (only present in some viruses).
2. Attachment Proteins - Also known as surface, attachment, or envelope proteins, these help viruses bind to host cells.
3. Enzymes - Some viruses carry enzymes, like reverse transcriptase, which allows them to convert RNA into DNA.
26
Resolution
Measure of microscope's ability to distinguish 2 points which are close together on an object
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Transmission electron microcope
Uses electromagnets to transmit a beam of electrons through a specimen. The denser parts absorb more electrons, so appear darker in the image formed.
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Scanning electron microscope
Scan a beam of electrons across the surface of a specimen. Reflected electrons are then used to form an image.
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Artefacts
Residue/ anything we are not viewing
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Difference between microcopes
1. S: no thin specimen (but still will be dead) T: thin specimen required (therefore specimen will be dead) O: specimen can be alive
2. S: electron beams bounce off the surface of the specimen T: electron beam penetrates the specimen; allowing us to see internal structures
3. S: 3D images T: 2D images
4. S: less complex staining process T: complex staining process O: complex staining process
5. S: image may contain artefacts T: no artefacts
6. S+T: black + white images O: colour images
7. S+T: higher resolution than O: (light has longer wavelengths than electrons)
31
What is cell fractionation?
The process of seperating cell organelles from each other
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During ultracentrifugation why must the solution be *ice-cold*?
To reduce enzyme activity that might digest organelles
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During ultracentrifugation why must the solution be *isotonic*?
To prevent the organelles from bursting/ shrinking due to osmosis
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During ultracentrifugation why must the solution be *buffered*?
To keep the pH constant and prevent the denaturing of enzymes
35
What is homogenisation?
The 1st step of cell fractionation: Breaking up of cells
- grind up or vibrates cells; breaks plasma membrane
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What is filtration?
The 2nd step of cell fractionation:
filtering cell debris/ unbroken cells from the organelles
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What is ultracentrifugation?
The 3rd step of cell fractionation:
The supernatant is centrifuged (spun) at high speeds so heavier organelles will collect at the bottom of the tube to be removed
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What is the Pellet?
Thick sediment at the bottom of the tube; contains heavier organelles
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What is the Supernatant?
Rest of the lighter organelles that are suspended in the solution above the pellet
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Weight order of organelles
1. Nucleus
2. Chloroplasts
3. Mitochondria
4. Lysosomes
5. Endoplasmic Reticulum
6. Ribosomes
41
Mitosis
Divison of a cell that results in each of the daughter cells having the same number of chromosomes as the parent cell and each other
42
What happens in the G1 (First Gap Phase)?
The cell grows larger, and copies organelles
43
What happens in the S Phase?
* Step 2 of Interphase
* Synthesises a copy of the DNA in it's nucleus and duplicates **centrosome**
[Centrosome: pulls chromatids apart. The core structure us made up of two **centrioles** aligned perpendicularly. The rest of the structure is the **spindle fibres**]
44
G2 (Second Gap Phase)
Cell grows more, makes proteins and organelles, and begins to rearrange contents for mitosis again; G2 ends when mitosis begins
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INTERPHASE
Occupies most of the cell cycle; sometimes known as resting phase due to no division taking place
46
NUCLEAR DIVISION
When the nucleus divides into two (mitosis) or four (meiosis)
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CYTOKINESIS
After/ follows nuclear division and is the process by which the cytoplasm divides to produce 2/4 new cells; part of TELOPHASE
