Chapter 2: Basic components of living systems Flashcards
What are the different types of microscopes?
- Light microscopes
*Transmission electron microscopes
*Scanning electron microscopes
*Laser scanning confocal microscopes
features of light microscope?
- Poor resolution due to long wavelength of light
*Living samples can be examined - Colour image can be obtained
features of TEM?
- high magnification and resolution
*electrons pass through specimen to create image
features of SEM?
*high magnification and resolution
*electrons bounce off the surface of specimen to create image
features of LSCM?
- high resolution
*3D imaging
*laser light is used to create image
what is the difference between resolution and magnification?
Resolution - the minimum distance between two objects in which they can still be viewed as separate.
Magnification - How many times larger the image is compared to the specimen
Formula for magnification?
magnification = image/ actual
types of sample preparations
- Dry mount
*Wet mount
*Squash slides
*Smear slides
Dry mount prep
Thin slices or whole specimens are viewed with just cover slip placed on top
wet mount
specimen added to water before lowering coverslip with a mounted needle to prevent air bubbles
squash slide
wet mounts which you push down on coverslip after to squash specimen to ensure a thin layer for light to pass is produced
smear slides
created using edge of another slide to smear sample to create thin, smooth, even coated specimen, coverslip placed on top after smear
staining
used to make certain cells and components more visible under a microscope
electron microscope
*a beam of electrons has a very short wavelength which means there will be a high resolution
*image is created using electromagnet
*EM must be in vacuum as electrons are absorbed by air therefore non living organisms can be visualised
cell theory
*both plant and animal tissue is composed of cells
*cells are the basic unit of all life
*cells only develop from existing cells
cell theory: 1665
cells first observed by Robert Hooke using thinly sliced cork
cell theory: 1674-83
first living cells observed
cell theory: 1832
evidence for the origin of new plant cells
cell theory:1833
nucleus first observed
cell theory: 1837-38
Birth of universal cell theory
cell theory: 1844
evidence for origin of animal cells
cell theory: 1860
spontaneous generation disproved
nucleus
the area where dna synthesis occurs, where lots of genetic material is found and is what controls the cell
* contains nucleolus
*contains chromatin
*contains nuclear envelope
*contains nuclear pores
nucleolus
an area within the nucleus and is responsible for producing ribosomes
* is composed of protein and rna
* used to produce ribosomes
chromatin
Uncondensed dna
*coils and condenses to form chromosomes
Nuclear envelope
two lipid bilayer membranes
nuclear pores
allows mRNA to leave nucleus
mitochondria/on
The site of aerobic respiration
*is the site of the final stages of cellular respiration, organic molecules are made available for the cell to use by the production of the molecule ATP
*a cell with more mitochondria is more active
*they have double membrane, inner is highly folded to form structures called cristae and the fluid is called the matrix
*contains small amounts of dna
lysosomes
*specialised forms of vesicles and contains hydrolytic enzymes
*Responsible for breaking down waste material in cells
*digest and breaks down bacteria and other pathogens and organelles
*involved in programmed cell death/apoptosis
vesicles
membranous sacs and have a storage and transport role
ribosomes
*small
*made up of 2 sub units of protein and rna
* 80s - larger ribosomes found in eukaryotic cells
70s - smaller ribosomes found in prokaryotic cells, mitochondria and chloroplasts
*are the site of protein synthesis
golgi apparatus
*compact structure formed of cisternae and doesn’t contain ribosomes
*modifies proteins and ‘packages’ them into vesicles (may be secretory vesicles if proteins intend to leave cell) or (lysosomes which stay in cell)
* protein enters as primary structure and leaves as a formed protein
*golgi vesicle - transport
centrioles
a component of the cytoskeleton present in most eukaryotic cells
* two centrioles form a centrosome
endoplasmic reticulum (ER)
a network of membranes enclosing flattened sacs called cisternae
rough endoplasmic reticulum (RER)
has ribosomes bound to surface and is responsible for the synthesis and transport of proteins
*secretory cells have more RER than cells that do not release protein
smooth endoplasmic reticulum (SER)
responsible for lipid and carbohydrate synthesis and storage
Flagella
used primarily to enable cells mobility
*used in some cells as a sensory organelle, detecting chemical changes in the cells environment
cilia
*can be mobile or stationary
*stationary cilia - present on thhe surface of many cells and is important in sensory organs such as nose
*mobile cilia, beat in rhythmic manner, creating a current and causing fluids or objects adjacent the cell to move
*mobile cilia is present in trachea to waft mucus away from the lungs
cytoskeleton
a network of fibres necessary for the shape and stability of a cell
*microfilaments - formed from the protein, actin. Is responsible for cell movement and contraction
*microtubules - globular tubulin in proteins polymerise to form tubes that determine the shape of a cell
Spindle fibres are also formed of microtubules
*Intermediate fibres - give mechanical strength to cells and help maintain integrity
vacuole
*filled with fluid surrounded by a single membrane called a tonoplast
*vacuole makes cell turgid and therefore provides support
*temporary store for sugars and amino acids
*the pigment may colour petals to attract pollinators
chloroplast
*surrounded by a double membrane
*contains thylakoids, folded membranes embedded with pigment.
*multiple thylakoids together are called a granum or grana(plural)
*fluid filled stroma which contains enzymes for photosynthesis
*stroma is where light independent reactions occur
*found in plant cells
cell wall
*provides strength to cell
*found in plant and fungi cells
*in plants - are made of cellulose
*in fungi - are made of chitin
*are freely permeable
*surrounds cell surface membrane
What are the key differences between prokaryotic and eukaryotic cells?
Prokaryotic cells lack a nucleus and membrane-bound organelles, while eukaryotic cells have a nucleus, membrane-bound organelles, and are larger.
What is the difference between light microscopes and electron microscopes?
Light microscopes use visible light to magnify objects, with a maximum resolution of 0.2 µm. Electron microscopes use electron beams and have a higher resolution, allowing for more detailed images
What is the function of the nucleus in a cell?
The nucleus contains the cell’s genetic material (DNA) and is responsible for controlling the cell’s activities, including growth, metabolism, and reproduction.
What is the function of the mitochondrion?
Mitochondria are the powerhouse of the cell, involved in energy production through aerobic respiration, generating ATP
What is the ribosome’s function in the cell?
Ribosomes are responsible for protein synthesis, translating mRNA into polypeptide chains
What is the function of the endoplasmic reticulum (ER)?
The rough ER synthesizes proteins that are secreted, incorporated into membranes, or sent to lysosomes. The smooth ER synthesizes lipids and detoxifies drugs and poisons
What is the role of the Golgi apparatus?
The Golgi apparatus modifies, sorts, and packages proteins and lipids for secretion or delivery to other organelles.
What does the lysosome do?
Lysosomes contain digestive enzymes that break down waste materials and cellular debris.
What is the function of the centriole in animal cells?
Centrioles play a key role in cell division by organizing the spindle fibers during mitosis and meiosis.
What is the structure of the plasma membrane?
The plasma membrane is composed of a phospholipid bilayer with embedded proteins, cholesterol, and carbohydrate chains, forming a fluid mosaic model.
What is the function of the plasma membrane?
The plasma membrane controls the movement of substances into and out of the cell, provides structural support, and facilitates communication between cells.
What are the key features of prokaryotic cells?
Prokaryotic cells are smaller, lack a nucleus, and have a single circular DNA molecule, 70s ribosomes, a cell wall (often made of peptidoglycan), and a plasma membrane. Some also have flagella
What is the function of the plasmid in prokaryotic cells?
Plasmids are small, circular DNA molecules that carry extra genes, such as those for antibiotic resistance, and are independent of the chromosomal DNA.
What are the three main components of the cytoskeleton?
The three components are microfilaments (actin filaments), intermediate filaments, and microtubules.
