Module 1 - Cells Flashcards
What is the brain of the cell?
Nucleus
What are the levels of biological organisation?
- The biosphere 2. Ecosystems 3. Communities 4. Populations 5. Organisms 6. Organs and Organ Systems 7. Tissues 8. Cells 9. Organelles 10. Molecules
What is the Biosphere?
Consists of all environments on Earth that are inhabited by life. Includes most regions of land, bodies of water and the atmosphere
What are ecosystems?
An ecosystem consists of all the living things in a particular area, along with all non-living things in which they interact with
What are communities?
The entire array of organisms inhabiting a particular ecosystem (called a biological community)
What are populations?
A population consists of all the individuals of a species living within the bounds of a specified area. The community’s definition is refined by a set of populations
What are organs and organ systems?
The architecture of complex organisms
What are tissues?
A group of similar cells that create a function
What are cells?
Life’s fundamental unit of structure to live
What are organelles?
Various functional components that comprise a cell
What are molecules?
A chemical structure consisting of two or more small chemical units called atoms, which perform various tasks within the cell.
What are emergent properties?
Properties that emerge once you zoom out of the levels of biological organisation, and thus see the bigger picture.
What is the opposite of emerging properties?
Reductionism - the ability to zoom in
What are the five unifying themes within the study of life?
Organisation Information Energy and Matter Interactions Evolution
What are the two main types of cells?
Prokaryotic and Eukaryotic
Define a Prokaryotic Cell
A single celled organism lacking a nucleus or other membrane-bound organelles.
What does DNA stand for?
Deoxyribonucleic acid
The two pairs that make up DNA?
AT CG
What is the fifth building block of nucleotides?
U
What is gene expression?
The entire process, by which the information in a gene directs the manufacture of a cellular product, is called gene expression
What is a genome?
The entire “library” of genetic instructions that an organism inherits
Order of gene expression?
DNA - (Transcription) - mRNA - (Translation) - Chain of Amino Acids - (Protein Folding) - Protein
What is genomics?
The study of whole sets of genes (or other DNA) in one of more specoes
What is proteomics?
The study of sets of proteins and their properties
What is a proteome?
The entire set of proteins expressed by a given cell or group of cells
What are bioinformatics?
The use of computational tools to store, organise and analyse the huge volume of data that results from high-throughput methods.
What are produces?
Plants and other synthetic organisms that pass chemical energy to consumers
What are consumers?
Organisms, such as animals, that feed on producers and other consumers
How many species have biologists discovered?
1.8 million
How many species of fungi have scientists discovered?
100,000
How many species of plants have scientists discovered?
290,000
How many species of vertebrate animals have scientists discovered?
57,000
How many species of insects have scientists discovered?
1 million
Three domains of life in the kingdom of life?
Bacteria, Archaea and Eukarya
What is bacteria?
The most diverse and widespread prokaryotes
What are Archaea?
Some of the prokaryotes known to live in Earth’s extreme environments, such as salty lakes and boiling hot springs
What are the four main domains of Eukarya’s?
Plantae, Fungi, Animalia and Protists
What are protists?
Most unicellular eukaryotes and some relatively simple multicellular relatives. (Scientists debate how to classify these organisms evolutionarily)
What is the mechanism of evolutionary adaption?
Natural selection
Can Bacteria have more than one cell?
No
Two types of Microscopy?
Light microscopy (LM) and Electron Microscopy (EM)
Three parameters in microscopy?
Magnification, resolution and contrast
In microscopy, what is magnification?
The ratio of the object’s size to its image size
In microscopy, what is resolution?
The measure of the clarity of the image
In microscopy, what is contrast?
The difference in brightness between the light and dark areas of the image
What does an Electron Microscopy do?
Focuses a beam of electrons through the specimen or onto its surface, as opposed to light.
What is a SEM?
Scanning electron micrograph
What does an SEM do?
Takes a 3d image of the surface of a specimen
What does TEM stand for?
Transmission Electron Micrograph
What does a TEM do?
Provides a thin section of a specimen
What do SEM and TEM’s use to bend the path of electrons?
An electromagnet
Disadvantage of using an EM?
You have to kill the cells in the process, which may also cause artefacts
What is the study of cell structure?
Cytology
What is cell fractionation?
Where you take a cell apart and separate major organelles and other sub-cellular structures from one another
What do you use for cell fractionation?
A centrifuge
What does a centrifuge do?
Spins test tubes holding mixtures of disrupted cells at a series of increasing speeds
What is fimbriae?
Attachment structures on the surface of some prokaryotes
What are ribosomes?
Complexes that synthesis proteins
What is the plasma membrane?
Membrane enclosing the cytoplasm
What is the cell wall?
Rigid structure outside the plasma membrane
What is the capsule?
Jellylike outer coating of many prokaryotes
What is flagella?
Locomotion organelles of some bacteria
Using a TEM, what must you use to stain the cell?
Heavy metals, which attach to certain cellular structures, thus enhancing the electron density of some parts of the cells more than others
What are the smallest cells known to man?
Mycoplasmas (between 0.1-1.0um)
Typical size of bacteria?
1-5um
Typical size of Eukaryotes?
10-100um
What does the plasma membrane do?
Functions as a selective barrier that allows passage of enough oxygen, nutrients and wastes to service the entire cell
How do phospholipids arrange themselves in a plasma membrane?
The hydrophobic parts of the phospholipids and membrane proteins are found in the interior of the membrane, while the hydrophilic parts are in contact with the aqueous solutions on either side.
Animal Cell: Define Flagellum
Motility structure present in some animal cells, composed of a cluser of microtubules within an extension of the plasma membrane
Animal Cell: Define Centrosome
Region where the cell’s microtubules are initiated; contains a pair of centrioles
Animal Cell: Define Cytoskeleton
Reinforces cell’s shape; functions in cell movement; components are made of protein.
What protein structures can you find inside a cytoskeleton?
Microfilaments Intermediate filaments Microtubules
Animal Cell: Define Microvilli
Projections that increase the cell’s surface area
Animal Cell: Define Peroxisome
Organelle with various specialised metabolic functions; produces hydrogen peroxide as a by-product then converts it to water
What does peroxide produce as a by-product? What does it turn it to?
Hydrogen-peroxide, then turns it to water
Animal Cell: Define Endoplasmic Reticulum (ER)
Network of membranous sacs and tubes; active in membrane synthesis and other synthetic and metabolic processes; has rough (ribosome-studded) and smooth regions
Three sections of the nucleus?
Nuclear envelope, nucleolus and chromatin
Animal Cell: Define Nuclear envelope
Double membrane enclosing the nucleus; perforated by pores; continuous with ER
Animal Cell: Define Nucleolus
Nonmembranous structure involved in production of ribosomes; a nucleus has one or more nucleoli
Animal Cell: Define Chromatin
Material consisting of DNA and proteins; visible in a dividing cell as individual condensed chromosomes
Animal Cell: Define Plasma Membrane
Membrane enclosing the cell
Animal Cell: Define Ribosomes
Complexes that make proteins; free in cytosol or bound to rough ER or nuclear envelope
Animal Cell: Define Golgi Apparatus
Organelle active in synthesis, modification, sorting and secretion of cell products
Plant Cell: Define Call Wall
Outer layer that maintains cell’s shape and protects cell from mechanical damage; made of cellulose, other polysaccharides, and protein
Plant Cell: Define Central Vacuole
Prominent organelle in older plant cells; functions include storage, breakdown of waste products, and hydrolysis of macromolecules; enlargement of the vacuole is a major mechanism of plant growth
What part of the cytoskeleton can be found in an animal cell, but NOT a plant cell?
Intermediate filaments
Plant Cell: Define Chloroplasts
Photosynthetic organelle, converts energy of sunlight to chemical energy stored in sugar molecules
Plant Cell: Define Plasmodesmata
Cytoplasmic channels through cell walls that connect the cytoplasms of adjacent cells
Aside from the nucleus, where else could DNA be found?
In the mitochondria and chloroplasts
Describe the nuclear envelope
Double membrane, each a lipid bilayer with associated proteins roughly 20-40nm apart. Pore structures are 100nm in diameter
What is a pore complex?
Lines each pore and plays an important role in the cell by regulating the entry and exit of proteins and RNA’s (as well as other things)
What lines the nuclear envelope, except at the pores?
Nuclear lamina
What is nuclear lamina?
Lines the nuclear envelope, and consists of a netlike array of protein filaments that maintains the shape of the nucleus by mechanically supporting the nuclear envelope.
What assists the nuclear lamina in maintaining the nuclear shape of the nucleus?
The nuclear matrix, a framework of protein fibres on the interior on the nuclear
What are chromosomes?
DNA organised into discrete structures that carry genetic information
What are chromatins?
Chromosomes formed with DNA and proteins, designed to reduce the length of the DNA to fit in the nucleus
What are ribosomes composed of?
Ribosomal RNA and protein
Are ribosomes membrane bounded?
No
Two types of ribosomes?
Bound and free
Describe the metabolic structure of Nucleoli and explain its function
Nucleoli consist of DNA and the ribosomal RNA (rRNA) made according to its instructions, as well as proteins imported from the cytoplasm. Together, the rRNA and proteins are assembled into large and small ribosomal subunits. (These are exported through nuclear pores to the cytoplasm, where they will participate in polypeptide-synthesis)
Main difference between smooth and rough er?
Protein synthesis occurs in the rough er, lipid metabolism in the smooth er
What enzymes do lysosomes release?
Phagyotic enzymes
Where can free ribosomes be found?
Suspended in the cytosol
Where are bound ribosomes found?
Attached to the outside of the endoplasmic reticulum or nuclear envelope
What can be found in the endomembrane system?
The nuclear envelope, the endoplasmic reticulum, the Golgi apparatus, lysosomes, various kinds of vesicles and vacuoles and the plasma membrane.
What are vesicles?
Membrane segments that contribute to the formation of the endomembrane system
What des the word and latin word for endoplasmic mean?
Without the cytoplasm Latin - little net
What are the ER tubules and sacs called?
Cisternae
Why is smooth ER smooth?
It lacks ribosomes
What are the functions of smooth er?
Synthesis of lipids, metabolism of carbohydrates detoxification of drugs and poisons, and storage of calcium ions
How does a muscle contract chemically?
Smooth ER membrane pumps calcium ions from the cytosol into the ER lumen, and when a muscle cell is stimulated by a nerve, calcium ions rush back across the ER membrane into the cytosol and trigger contraction of the muscle cell.
What are most secretory proteins in the rER?
Glycoptroteins
What are glycoproteins?
Proteins with carbohydrates covalently bonded to them
What is the Golgi Apparatus composed of?
Flattened membranous sacs called Cisternae
Two sides of a Cisternae?
Cis (on the same side) face and Trans (on the opposite side) face
How do lysosomes work?
Filled with hydrolytic enzymes, and a high ph, that digests macromolecules. Too many leaking lysosomes can self digest a cell
What is the word for a unicellular eukaryote engulfing a smaller organism?
Phagocytosis
What is a white blood cell called?
A macrophage
What is autophagy?
When a cell uses lysosomes to recycle its own organic material, releasing it into the cell’s cytoplasm
How often does a liver cell renew itself?
It recycles half its macromolecules a week
Where are vacuoles derived from?
The endoplasmic reticulum and Golgi apparatus
What is the Endosymbiont theory?
This theory states that an early ancestor of eukaryotic cells engulfed an oxygen-using nonphotosynthetic prokaryotic cell
What is the name of a cell living within another cell?
Endosymbiont
Infoldings in the inner mitochondria are called?
Cristae
Second layer of the mitochondria’s membrane is called?
The mitochondria matrix
What are stacks of thylakoids called?
Granum
What are the sacs inside a chloroplast called?
Thylakoids
What is the fluid outside the thylakoids in a chloroplast called?
Stroma
What is the chloroplast a specialised member of? (What family of plants?)
Plastids
What is a peroxisome?
A specialised metabolic compartment bounded by a single membrane. They contain enzymes that remove hydrogen atoms from various substrates and transfer them to oxygen, producing hydrogen peroxide (H202)
What are peroxisomes used for?
Some to break down fatty acids to use for ATP in the mitochondria, sometimes they detoxify alcohol.
How does the cell not die from hydrogen peroxide as a by product of a peroxisome?
It converts it to water
How does a cell retain mobility?
Interaction of the cytoskeleton with motor proteins
Structure of a microtubule?
Tubulin polymers Hollow tues
Strcture of microfilaments?
Actin filaments Two intertwined strands of actin
Structure of intermediate filaments?
Fibrous proteins coiled into cables
What type of cytoskeleton anchorages the nucleus?
Intermediate filaments
What are microtubules?
Hollow rods constructed from a globular protein called tubulin. They shape and support the cell and also serve as tracks along which organelles equipped with motor proteins can move. The guide vessels from the ER to the Golgi, and furthermore to the plasma membrane, and also help in separation of chromosomes during cell division.
What are microtubules made from?
A protein called dimer. A dimer is slip into two subunits, a-tubulin and B-tubulin
Where do microtubules for from?
A centrosome
What are centrioles?
Within a pair of centrosomes, nine sets of triplet microtubules arranged in a ring help organise the chromosome.
What are flagella and cilia made from? What is the difference between the two?
Cilia is a plural of flagella, and they are made from microtubules
How is a flagellum/cilia anchored in the cell?
By a basal body, with microtubule triplets in a “9+0” pattern
What motor protein is responsible for bending cilia?
Dyneins
What is the cytolasmic outer layer of a cell called?
The cortex
What is the primary cell wall?
A relatively thin and flexible wall a new plant cell begins with
What glues cell walls to one another?
Middle lamella
What is middle lamella composed of?
A thin layer rich in stick polysaccharides called pectins
What is a secondary cell wall?
The hard, durable matrix that builds between the primary cell wall and the plasma membrane. Wood has many SCW’s
What is the most abundant glycoprotein in the ECM in animals cells?
Collagen (40%) of total protein in human body
What is a proteoglycan?
A molecule consisting of a small core protein with many carbohydrate chains attached
What are integrins?
Membrane proteins with two subunits, bind to the ECM on the outside and to associated proteins attached to microfillaments on the inside. This linkage can transmit signals between the cell’s external environment and its interior and can result in changes in cell behaviour.
What is fibronectin?
Attaches the ECMto integrims embedded in the plasma membrane.
What are the channels of communication between plant cells called
Plasmodesmata
Three types of junctions in an animal cell?
Tight junctions, desmosomes and gap junctions
What are tight junctions?
The plasma membranes of neighbouring cells are very tightly pressed against each other, bound together by specific protein. Forming continuous seals around the cells, tight junctions establish a barrier that prevent leakage of extracellular fluid across a layer of epithelial cells. Fo example tight junctions between skin cells make us watertight.
What are desmosomes
Anchoring functions function like rivets, fastening cells together into strong sheets. Intermediate filaments made of sturdy keratin proteins anchor desmosomes in the cytoplasm. Desmosomes attach muscle cells to each other in a muscle. Some “muscle tears” involve the rupture of desmosomes.