Cell Theory Unit 2 Flashcards
What is the definition of cell theory?
States that organisms consist of cells & the products of cells, & that all cells come from pre-existing cells
How are cells studied/viewed two(2)?
With light microscopy, and transmission electron microscopy
How can cells be separated into seperate contents in a physical method?
Using a centrifuge, and then using biochemical techniques to study the fractioned components with speed & time
What are the two(2) components in a capsule after a centrifuge?
Supernatant, and the nuclei/cellular debris in the bottom
What is the last method of cell study?
Genetics and transcriptomics (cell gene expression)
Define prokaryotic cells and their cells?
Include bacteria & archaea. Are smaller, non-compartmentalised, w/ no nucleus or cytoskeleton, and have small genomes (most species 1500-4000 genes)
Define eukaryotic cells and their cells?
Protists, plants, animals, and fungi. They’re larger, membrane bound w/ compartmentalisation of functions, have a nucleus & a cytoskeleton, and have larger genomes (6,000-25,000 genes)
What is the plasma membrane?
A selective barrier (permeable) that allows some things to pass through, but not others
What also possesses a membrane in eukaryotic cells?
organelle membranes also have selective barriers (permeable), contributing to compartmentalisation
What is the nucleus and how many membranes does it have?
The nucleus is an area where chromosomes are located and where genes are transcribed. It has two(2) protecting membranes
What four(4) components make up the nucleus?
Chromatin (organised into chromosomes), 50/50 DNA & Protein, Nucleolus (ribosomal RNA transcribed and where ribosomes begin, Enzymes that work on DNA, Nuclear lamina
What is the main function of the ribosomes?
It’s where protein synthesis takes place
There are two(2) subunits of ribosomes, what are they?
A larger one, and a smaller one, both composed of ribosomal RNA & many proteins
Where are the free ribosomes located, and the bound ribosomes located?
Free ribosomes are located in the cytosol, and bound ribosomes are attached to the endoplasmic reticulum (rough ER)
Where will proteins from the ribosome be active five (5)?
Cytosol, chloroplast, mitochondrion, nucleoplasm, and peroxisomes
What is the endomembrane system, and what processes is it involved in?
A network of elements connected or by means of transport vesicles. They’re involved in synthesis, modification, packaging, and shipping proteins bound for destinations
What six(6) organelle systems are a part of the endomembrane system?
Nuclear Envelope, Endoplasmic reticulum (rough & smooth), transport vesicles, golgi apparatus, lysosomes, and the vacuole
What is the function of the rough ER, and the smooth ER?
Rough ER- bound ribosomes, translating proteins
Smooth ER- lipid synthesis & toxic substances removal, transport vesicles to golgi
What is the function of the Golgi Apparatus?
Helps process and package proteins and lipid molecules, especially proteins destined to be exported from the cell
What is the function of lysosomes?
Make enzymes that perform hydrolytic reactions, digest food (pH of 5). Can be harmful if leaked
What is the function of the vacuole, and what cells is it limited to?
Help sequester waste products, contains pigment, hydrolytic enzymes aid in breaking down materials, cheap growth via water absorption (swelling to increase size)
What is the main function of the Mitochondrion?
Provides most of the ATP needed for the cell to function
What contains DNA and can split off into different structures via mitosis
Mitochondrion & Chloroplasts
How did the mitochondrion in cells form?
It arose as an individual prokaryotic cell (anaerobic bacteria), engulfed by a eukaryotic cell then to function. Chloroplasts had similar instance
The mitochondrion is bound by a membrane, what are the two(2) membranes called?
Outer membrane, and inner membrane (mitochondrial matrix (ATP generationg), and the inner mitochondrial membrane(proton accumulation))
Why does the interior of the mitochondrion have so many folds?
Greater surface area for different processes
How/why can the mitochondrion have its own genome and start gene expression?
Formally an independent cell (anaerobic bacteria)
What is a plastid, and where is it found?
A double membraned organelle that stores and produces food (chloroplast photosynthesis) or contains pigment (green), found in plants and algae
What are four(4) components of the structure of a chloroplast?
Thylakoid membrane (site of proton accumulation), Stroma (rxns w/ CO2 into biosphere take place), double membrane, and circular DNA (150 genes)
What is the function of the thylakoid membrane?
Site of light dependent photosynthesis w/ the membranes embedded into the chloroplast membrane
What is the stroma?
Colourless fluid surrounding the grana within the chloroplast (thylakoid membrane)
What is a granum?
A stack of thylakoids
How do the mitochondrion and chloroplast make ATP?
Use the energy released from electron transport to create a proton gradient (electrochemical gradient)
What is the function of the cytoskeleton? (3)
It helps support cells mechanically/maintain shape, enables changes in cell shape, & it provides movement in the cell as a whole (moves chromosomes)
What macromolecule makes up the cytoskeleton?
Proteins and protein filaments
Other than the cytoskeleton what also provides movement in the cell?
Cilia, ameboid motion, & flagellum
What is the function of the intermediate filaments (tough protein fibres)? (2)
Filaments in the cytosol provide shape to the cell, filaments form the nuclear lamina that lines the nucleoplasmic face of the nuclear envelope
What are microtubules apart of?
The cytoskeleton (cylinder shape)
What are microtubules constructed of ( two proteins), and what two(2) proteins are they associated with?
Constructed of alpha & beta tubulin heteromdimers, and associated w/ dyneins and kinesins motor proteins
What is an important function of microtubules? (3)
Form tracks for the motor proteins for vesicle movement in the cell, move chromosomes around during mitosis/meiosis, & form the core of flagella and cilia
Can chromosomes move on their own?
No, they rely on microtubules for movement within the cell
What shape is an actin microfilament, and how do they relate to microfilaments?
Double helix, and microfilaments are polymerised actin molecules
What does the actin-myosin reaction underly in the cell? (4)
Muscle contraction, cytoplasmic streaming, cell crawling, and animal cell cytokinesis (dividing of cell into 2)
What motor protein interacts w/ actin?
Myosin
What is the plant cell wall constructed of?
Cellulose microfibrils in a matrix of other polysaccharides and proteins
What are four(4) functions of the plant cell wall?
Protection, maintenance of cell shape, structural support for the whole plant, and prevention of excess water uptake
Give an example of cellulose and lignin.
Cotton, and wood
What is plasmodesmata?
small channels that connect the cytoplasm of neighbouring plant cells to each other, establishing living bridges between cells.
What are the intercellular junctions (3) at the animal cell surface?
Tight junctions- diffusion barriers (sealing space)
Desmosomes- strong connections (intermediate filaments)
Gap junctions- communication junctions (emit ions & small molecules btwn cells)
What makes up the extracellular matrix? (3)
Glycoproteins (collagens), proteoglycans, and other proteins cross-linked to one another by extracellular adhesion proteins
What happens to surface area/volume ratio as the cell increases in size?
It decreases
What size cell transports materials into and out of a cell quicker, small or large?
Small cells
What happens to cells surface/volume ration with increased sphericity?
The surface/volume ration decreases
Is there a limit to the amount of products of gene expression that can be produced in one nucleus?
Yes
The time of diffusion in molecules is proportional to?
(Distance)^2
What happens to very large cells, what is their role?
They either become metabolically inactive, or they are non spherical, or they have many nuclei
Name the structure(s) in the cell where the following activities take place. a) protein synthesis; b) photosynthesis; c) synthesis of proteins to be secreted from the cell; d) storage of genetic information; e) synthesis of small and large ribosomal subunits; f) hydrolysis and recycling of damaged organelles; g) phospholipid synthesis.
a) ribosome; b) chloroplast; c) rough ER; d) nucleus (chromatin); e) nucleus (nucleolus); f) lysosome; g) rough ER and smooth ER.
How many lipid bilayers would a water molecule cross if it travelled from the interior of the nucleus, out to the cytoplasm, all the way through a mitochondrion, to the exterior of the cell? Assume the water molecule does not pass through a nuclear pore or any transport protein.
7
How does a secreted protein get outside the cell without crossing a membrane?
A secreted protein is synthesized in the rough ER: the ribosome doing the protein synthesis is attached to the ER membrane, and the nascent polypeptide is fed into the lumen of the ER as it is being made. Once made, the protein stays inside the ER until a vesicle blebs off the ER carrying it, and makes its way to the trans face of the Golgi apparatus. When the vesicle fuses with the Golgi membrane, the protein finds itself in the lumen of that Golgi cisterna. There, the protein is modified as the cisterna matures, and another vesicle pinches off, carrying the protein in its lumen to the plasma membrane. After one final membrane fusion event, the protein is outside the cell. Because of these membrane fusion events, the protein gets outside the cell without ever crossing a membrane.
What cytoskeletal elements are involved in the following activities? a) movement of chromosomes during mitosis and meiosis; b) operation of cilia and flagella; c) maintenance of nuclear shape and position; d) muscle contraction; e) cytoplasmic streaming; f) traffic of vesicles between the Golgi apparatus and the plasma membrane.
a) microtubules; b) microtubules; c) intermediate filaments (nuclear lamina); d) microfilaments (actin); e) microfilaments (actin); f) microtubules.
How can adjacent cells in plants and animals communicate with each other?
Two ways. First, a cell could secrete a chemical signal across its plasma membrane, which might diffuse to a receptor in the plasma membrane of the neighbouring cell. Second, substances dissolved in the cytosol of one cell could travel directly to the other cell through cytoplasmic connections between the cells – plasmodesmata in plants, gap junctions in animals.
What is a granum?
A stack of thylakoids
How is ATP manufactured in the mitochondrion/chloroplast?
Energy from the electron transport is used to create a proton gradient (push protons against a gradient), this is potential energy
