Cellular Life Flashcards
What are biomolecules?
Chemicals made inside a living thing that is involved in the maintenance and metabolic processes of living organisms
What element do all biomolecules contain?
Carbon
What are the four major types of biomolecules?
Carbohydrates.
Lipids.
Proteins.
Nucleic acids.
List two nucleic acids
DNA and RNA
What are nucleic acids?
Long polymers made of repeating units of nucleotides
What are the main functions of nucleic acids?
To store and transfer genetic information
To use the genetic information to synthesize new protein
RNA such as m-RNA takes genetic message from RNA
Why are proteins important on a cellular level?
(Products of genes)
- Catalysts to promote replication (Enzymes)
Why are lipids important on a cellular level?
Give structure
Why are carbohydrates important on a cellular level?
Provide energy for growth & replication
What are the Properties of Life
Order/Organization Adaptation Responsiveness Reproduction & Heredity Growth Obtain/Use Energy Control/Regulation
What are the molecular processes which aid the common features of living organisms
Metabolism
Replication
What is metabolism?
The total sum of all chemical reactions in the body – the balance of anabolism and catabolism
What is the purpose of metabolism?
Converts the fuel in the food we eat into the energy needed to power everything we do, from moving to thinking to growing.
It maintains the living state of the cells and the organism
What is replication?
DNA replication is the biological process of producing two identical replicas of DNA from one original DNA molecule. This process occurs in all living organisms and is the basis for biological inheritance.
What is the purpose/significance of DNA replication?
If DNA never replicated, meiosis and mitosis would slowly halve the size of the genome until each cell would die.Therefore, it is important that DNA doubles itself to account for the cells splitting during mitosis/meiosis.
What is life?
The capacity for growth and self-replication
What are the processes which allow growth?
Metabolism
Maintainance of order
Response to stimuli
What is the process which allows for self-replication?
Inheritence of genetic material
What biomolecules are involved in the growth of an organism
Proteins
Carbohydrates
Lipids
What biomolecules are involved in the self-replication of DNA in an organism?
Nucleic Acids - DNA and RNA
What is the central dogma of molecular biology?
It describes the two-step process, transcription and translation, by which the information in genes flows into proteins: DNA → RNA → protein
What are the catalytic events supporting the transmission of genetic information?
Metabolism
Growth
Response to Stimuli
What facilitates the transmission of genetic information and processes to support it
Cell structure
What are the three common features of cells?
Nuclear Region
Plasma Membrane
Cytoplasm
What is the nuclear region and what is it’s function
Area of a cell where most of its genetic material is found (DNA)
Allows DNA Replication & DNA Transcription
What is the Plasma Membrane and what is it’s function
Separates cell from outside
Maintains order
Allows transport
What is the Cytoplasm and what is it’s function?
It contains multiple organelles & sites of catalytic action to support metabolic activities required for growth & replication
What biomolecules are present in the nuclear region?
DNA + RNA + Protein
What biomolecules are present in the cytoplasm?
Lipid and Protein
Give a function of the nucleus
Contains, decides & sends out the instructions for cell behaviour
Controls gene expression and mediate the replication of DNA during the cell cycle
Where is the genetic information contained in bacteria?
Cytoplasm
Where is the genetic information contained in Eukaryotes?
Genetic information (DNA) contained within nuclear membrane separated from cytoplasm
What are the three domains in the three domain system?
Bacteria
Eukarya
Archaea
List five differences between Prokaryotes and Eukaryotes
P = no true nucleus and no membrane bound organelles – metabolism in cytoplasm nuclear region called “nucleoid” no membrane separating it cell Wall gives structure & rigidity smaller cells E = true nucleus within nucleus, nucleolus region no Cell Wall – more fluidic shape contain organelles (Mitochondria) larger cells
What is the nuclear envelope?
It is a highly regulated membrane barrier that separates the nucleus from the cytoplasm in eukaryotic cells
What is the nucleolus?
Area rich in ribosomal RNA
obvious under microscope
How is chromosome made visible
Only visible in replicating cells
What are the structures in the the Nucleus/Nuclear Region
Nuclear Envelope, Nucleolus, Chromosomes
What is the nuclear envelope made of?
Phospholipid bi-layer forms a Nuclear Membrane studded with Nuclear Pores
What is the function of the nuclear envelope?
Allows transport of RNA, proteins, carbohydrates
What is the function of the nucleolus?
The nucleolus primary function is to assemble ribosomes
How does the double helix structure aid the DNA processes DNA replication and DNA transcription
- DNA REPLICATION – whole genome unwinding & copying chromosomes
- DNA TRANSCRIPTION – regulated unwinding of specific genomes, creation
of “RNA” copy
What is a nucleosome and what is it made up of?
- The smallest DNA bundle
- DNA + Histone Protein
What is the chromatin made up of?
Nucleosomes (DNA + Histone)
What are chromosomes made up of?
Chromosomes are made up of a DNA-protein complex called chromatin that is organized into subunits called nucleosomes.
What is the template, Catalyst and Product of Transcription
Template : DNA (Gene)
Catalyst : RNA polymerase (protein enzyme)
Product : messenger RNA (mRNA)
Give four differences between DNA and RNA
DNA : double stranded SUGAR COMPONENT – Deoxyribose Thymine as base Stable Structure RNA : single strand SUGAR COMPONENT – Ribose URACIL as base Unstable, short-lived
Does all RNA get turned/translated into Proteins?
No
Why doesn’t DNA directly translate into protein?
If DNA would directly have to translate into protein, there is a high risk of the loss of genetic material. Also DNA is very tightly packed, so unwinding it every now and then will not be energy efficient
What are the fates of RNA?
mRNA : Exported from Nucleus to sites of Protein synthesis (Ribosomes)
rRNA : Forms a complex with proteins - Ribosomes
tRNA : RNA species that links up with Amino acids -> proteins
Found in Ribosomes
Where are ribosomes found (both eukaryotic and prokaryotic?)
Found in Pro and Euk
Why are ribosomes important?
They are central in flow of genetic information
What are the functions of ribosomes?
Translate mRNA into PROTEINS
Forms complex of rRNA, proteins, tRNA & mRNA
Where are ribosomes found in the cell
Ribosomes are found ‘free’ in the cytoplasm or bound to the endoplasmic reticulum (ER) to form rough ER
Where are ribosomes found in a prokaryotic cell?
Since there are no membrane-bound organelles in prokaryotes, the ribosomes float free in the cytosol
What is the template, catalyst and product of translation?
Template : mRNA (Nucleotides)
Catalyst : RIBOSOME (protein & RNA
complex)
Product : Protein (Amino Acids)
What is the fate of the protein produced by DNA
Enzymes
Hormones
Antibodies
What occurs in the nucleus during protein synthesis?
DNA resides
mRNA made
What occurs in the cytoplasm during protein sythesis?
(Ribosome) mRNA translated into protein
Where do the proteins go?
The Cytoplasm
The Endomembrane System
The Plasma Membrane
Organelles with a Prokaryotic Origin
What does the cytoplasm consist of?
Includes the fluid known as cytosol, the supportive structure known as the cytoskeleton and membrane bound organelles
What is the cytosol and what is it mainly made up of?
Intracellular fluid inside the cell (transparent) and Mainly water, ions, biomolecules/metabolites & proteins
Is the cytosol and cytoplasm the same thing?
The cytoplasm is made up of the cytosol and insoluble suspended particles. The cytosol refers to the water and anything that is soluble and dissolved in it such as ions and soluble proteins. The insoluble suspended particles could be things like ribosomes. Together, they make up the cytoplasm
What are the functions of the cytosol?
Metabolic function - Concentration Gradients of Biomolecules
Contains Protein Complexes (Inflammasomes/Apoptosomes/Centrosomes)
used in cell signalling/division
Contains cytoskeleton proteins - Shape, Structure & Motility
What are the three Cytoskeletal proteins?
Microfilaments, microtubules, intermediate filaments
What’s another name for Actin filaments?
Microfilaments
What is the function of the cytoskeleton?
It provides structure and shape to cells
Intracellular transport - The movement of vesicles and substances within the cell. Intracellular transport heavily relies on microtubules for movement
Actin filaments are the ____ cytoskeletal filaments in eukaryotic cells
smallest
Give an example of microfilaments
Actin
Example of microtubules
Tubulin
Example of intermediate filaments
Keratin
A Role of Cytoskeleton: Serves as a scaffold providing _______ ______ and maintaining ______ _____
structural support; cell shape
What is the shape of microtubules
Hollow, cylindrical structures.
The distribution of which cytoskeleton protein determines the shape of the cell and how?
Microtubules
Microtubules facilitate movement of ____ between compartments.
vesicles
What is the function of microtubules
Involved in cellular organization
Centrosome - In mitosis the nuclear membrane breaks down and the centrosome nucleated microtubules can interact with the chromosomes to build the mitotic spindle.
What is the function of Intermediate filaments?
Anchor organelles & organize 3-D shape
What is the function of the microfilaments?
Cellular growth as actin filaments polymerizes
& depolymerizes at opposite ends
What is the Endoplasmic Reticulum?
A network of membranes found throughout the cell and connected to the nucleus
The endoplasmic reticulum consist of folds, what are they called and what are their function
Cisternae, Pack and modify proteins and polysaccharides
Package the proteins and then send them to transport carriers.
Package polysaccharides that are synthesized in the Golgi apparatus.
Is the Endoplasmic Reticulum found in eukaryotic or prokaryotic cells?
Eukaryotic
What are the two types of Endoplasmic Reticulum?
Rough and Smooth Endoplasmic Reticulum
What is the difference between rough ER and smooth ER?
Rough ER – studded with Ribosomes, series of flattened sacs.
Smooth ER – no Ribosomes, tubule network
What is the function of rough ER?
sites of protein synthesis
What is the function of smooth ER?
important in lipid synthesis & detoxification
The ER doesnt reach the plasma membrane directly, how does it do this?
Vesicles bud off – (membrane bound) &
transport contents around & out of cell
What is the function of the Golgi Apparatus?
Directs/Sorts traffic inside the cell
The New membrane-bound organelles bud off golgi, but where do they go?
Lysosome
Plasma membrane
Secretory Vesicles
Why do the new membrane- bound organelles bud off golgi and go to lysosome?
for recycling
Why do the new membrane- bound organelles bud off golgi and go to Plasma membrane?
For Transport Functions
Why do the new membrane- bound organelles bud off golgi and go to Secretory Vesicles
For secretion/export (eg - Exosomes - extracellular vesicles)
What is the function of smooth er in relation to the Golgi Aparatus?
Traffics lipid to Golgi
What is the function of rough er in relation to the Golgi Aparatus?
Delivers protein cargo to Golgi
What is the function of the Golgi Aparatus?
It is another packaging organelle like the endoplasmic reticulum (ER).
It directs & sorts trafficking of
proteins within & out of the cell via the Plasma Membrane
What is the Cis face of the Golgi Aparatus?
Nuclear side
What is the Trans face of the Golgi Aparatus?
Plasma membrane side
What is Endocytosis?
Endocytosis occurs when the cell membrane engulfs particles outside the cell, draws the contents in, and forms an intracellular vesicle called an endosome.
What is an endosome?
Endosomes are a heterogeneous collection of organelles that function in the sorting and delivery of internalized material from the cell surface and the transport of materials from the Golgi to the lysosome or vacuole.
Why is Endocytosis crucial to the survival of a cell?
Since most molecules important to the cell cannot normally pass through the cell’s hydrophobic plasma membrane, endocytosis is needed
What needs to occur in order for endocytosis to happen?
Substances must be enclosed within a vesicle formed from the cell (plasma) membrane
What organelle builds lysosomes?
Golgi Aparatus
Where is the golgi aparatus found?
They are located very near the rough endoplasmic reticulum and hence near the nucleus.
What transports lipids and proteins to the Golgi Aparatus?
Transport Vesicles
Is the Lysosome highly acidic or basic and why?
Highly Acidic - Contains degradative enzymes (work at
acidic pH)
Why do the substances entering in vesciles enter the lysome?
For degredation - Lysosomes contain a wide variety of acidic enzymes that break down macromolecules such as nucleic acids, proteins, and polysaccharides.
What is the lysosome made up of?
Enzymes and a membrane
What are the other functions of the lysosome?
Important in response to pathogens (PHAGOCYTOSIS)
Important in recycling old organelles (AUTOPHAGY)
What is the problem that arises in the cytoplasm in terms of seperation of organelles.
Cytoplasm – mainly water,
Proteins
Some nucleic acids (RNA)
(Hydrophilic environment)
What does Hydrophilic mean?
Water soluble
How do you chemically achieve the seperation in the cytoplasm
Need something that won’t mix with these polar molecules to provide separation (NON-POLAR)
(Hydrophobic environment)
What is Hydrophobic?
Hydrophobes are nonpolar molecules and do not interact with water molecules.
What biomolecule provides the solution to this seperation crisis in the cytoplasm and why?
Lipids - Lipids can have hydrophobic & hydrophilic
portions (amphipathic) which is ideal for use in membranes
What is amphipathic?
It has both hydrophilic and hydrophobic parts.
What is a phospholipid?
It contains a phosphate head – water soluble/hydrophilic/polar
2 Fatty Acids (C/H chain) tails – hydrophobic/non-polar, insoluble
Give an example of a phospholipid
Phosphatidylcholine Choline Phosphate Glycerol Two fatty acids
Why are phospholipids important?
Due to its hydrophobic and hydrophilic parts, they play a key role in determining what enters and exits every cell. They make up your cell membranes and is critical to a cell’s ability to function
What is a micelle structure?
Circular arrangement of phospholipids where the hydrophilic tails are attracted to each other & mix with external soluble environment
Hydrophobic tails are attracted to each other
What is a bilayer structure?
Flat-sheet containing 2 layers of phospholipids
Hydrophobic tails attracted to each other
Exposing the Hydrophilic Heads to the external and internal water soluble environment
What is the function of the Hydrophobic tails?
Provide separation
What is the function of the Hydrophilic heads?
Allow mixing with the environment
Why does the phospholipid bilayer want to form a ‘‘circular/enclosed’’ shape?
Linear shape with exposed ends will not work - energetically unfavourable and is ideal for cell shape
What is the advantage of the aphilic nature of phospholipids?
Allows Fluidity - permits Growth, Expansion, Transport
Why do phospholipids move laterally?
Fatty acid chains in the phospholipids are often unsaturated, so that they don’t pack together tightly
How do phospholipids in the cell membrane move?
Individual phospholipids can rotate and move laterally within a bilayer
Which hydrophobic lipid can become embedded in the plasma membrane and what does it do?
Cholesterol - provide extra stability
How does Cholesterol provide extra stability?
It slightly immobilizes the outer surface of the membrane and makes it less soluble to very small water-soluble molecules that could otherwise pass through more easily. Without cholesterol, cell membranes would be too fluid, not firm enough, and too permeable to some molecules
How does water transport across the Lipid bi-layer?
Osmosis
Why is it difficult for polar molecules to cross the bi-layer?
Because of the hydrophobic centre
Out of the three - water, polar moleules and non polar molecules- which can pass through the membrane the easiest
Non-polar small molecules - because of the hydrophobic core
What is the function of Protein Transporters in cell membrane?
Protein Transporters assist the transport process in cell membranes:
Ion Channels/Transporters – permit entry
Receptors – detect substances and initiate cellular responses
Some allow passive diffusion through Carrier
Some requires energy/stimulation
How does the Cellular Transport System facilitate transport?
Production of Vesicles from Golgi to transport proteins out (Secretion & Exocytosis)
Substances can enter via Endocytosis (Pinocytosis - nutrients)
What does the Bacterial Cell Wall consist of?
Lipid, lipoprotein, carbohydrate/sugar species
Some bacteria have second “plasma membrane” outside their cell wall, what is the benefit of this?
Allows more specificity/selectivity
Why are the Cell Wall & Membrane components of bacteria often targeted by antibiotics
Associated with immunogenicity and
pathogenicity
Some bacteria possess polysaccharide outside cell wall, what is it called?
Capsule - protect the bacteria cells from environmental dangers such as antibiotics and desiccation
Bacterial kingdom divided into 2 Groups based on what?
Cell Wall Structure
How they stain under biochemical assays (Gram stain)
List three differences between a gram positive and gram negative bacteria
Gram negative : - Outer membrane with lipids/lipoprotein & transport proteins - Thin cell wall of peptidoglycan (stain negative) - Contains periplasmic space Gram positive : - No outer membrane - Major Peptidoglycan (carbohydrate polymer) cell wall (Stain positive – retain counterstain) - Smaller periplasmic space
Plants cells have a thick cell wall, what is it made of and what is its function?
Cellulose cell wall (carbohydrate polymer)
Confers stability & protection
Survives high osmotic pressure
Plants have a three layer structure, what is it made up of?
- Plasma membrane (inside)
- 3 layers of cellulose “primary wall”
- Outer “middle lamella”, forms the
division/border with neighbouring cell
What is the function of mitochondria and how does it do this?
Allows cellular respiration,
Breakdown of Glucose (cytoplasm) &
other intermediates (matrix) to generate
energy via oxidative phosphorylation
What is the function of the christae?
Contain proteins and molecules that participate in cellular respiration.
Where is the mitochondria’s DNA (Plasmid-like) & Ribosome found?
in the “Mitochondrial matrix’’
What does the mitochondrion consist of structurally?
Outer membrane
Inner membrane
Gel-like material called the matrix
How many membranes are present in the mitochondria?
Two - Double membrane system (sim to prokaryotic system)
Where are mitochondria found?
All free-living eukaryotes
Where are chloroplasts found?
Plant & Algae only
How many membranes are present in chloroplasts?
Two - Double membrane system
Where is chlorophyll found in chloroplasts?
Chemical found in internal membrane network “Thylakoids”
What are thylakoids?
A thylakoid is a membrane-bound compartment inside chloroplasts and cyanobacteria. They are the site of the light-dependent reactions of photosynthesis
Where are the chloroplasts own DNA (Plasmid-like) & Ribosomes found?
In the “Stroma”, colorless fluid surrounding the grana within the chloroplast
Function of chloroplasts
Allows Photosynthesis, Captures light energy, fuel enzymatic formation of Glucose (req CO2/H20)
What is the mitochondrial eve and why is it possible?
The Mitochondrial Eve is the matrilineal most recent common ancestor of all currently living humans. Fertilized Egg - Cytoplasm & its contents solely from Mother
All Mitochondria travel through maternal line
What two factors lead to different types of cell division arising in living things?
- Different Cells have different structures
- DNA is organized very differently in different cells
What are the three types of cell division?
Binary Fission
Budding
Mitosis
In what living things does Binary Fission occur?
Bacteria
What are the key factors of living things who divide by binary fission?
- No nucleus
- 1 “bacterial chromosome”
- Duplicates by replication
In what organisms does budding occur?
Diatoms and some yeasts
What are Diatoms?
Diatoms are a major group of algae, specifically microalgae, found in the oceans, waterways and soils of the world.
What are the key features of organisms which divide by budding?
- Have nuclei & chromosome (s)
- Cell Walls
- Nuclear envelope remains intact
- Chromosomes duplicates & separate
What are the key features of organisms which divide by mitosis?
- Have nuclei & multiple chromosomes
- No Cell Wall
- Nuclear envelope dissolves
- Chromosomes duplicates & separate
- Nuclear envelope reforms
In what organisms does mitosis occur?
Most eukaryotes
In what type of cells does mitosis only occur?
Somatic cells
What is DNA replication?
Duplication & separation of the chromosome(s)
What is Cytokinesis?
Cytoplasmic events required to separate chromosomes & divide the cytoplasm
Where does DNA replication occur in eukaryotic cells?
DNA replication occurs in the nucleus of eukaryotic cell.
Where does DNA replication occur in prokaryotic cells?
Because prokaryotic cells do not have nuclei, DNA replication occurs in the cytoplasm of a prokaryotic cell.
What is the result of mitosis?
- 1 cell gives rise to 2 daughter cells with identical genetic complement
What is the cell cycle?
The cell cycle, or cell-division cycle, is the series of events that take place in a cell leading to its division and duplication of its DNA to produce two daughter cells
What is mitosis refered to in the cell cycle?
M-phase
What is the Non Mitotic phase of cell?
Interphase
What is Interphase broken up into?
- G1
- S
- G2
In which part of interphase does DNA replication occur?
S
What is the mitotic phase broken up into?
Cytokinesis
Mitosis
What are the different phases in mitosis?
- Prophase
- Pro-Metaphase
- Metaphase
- Anaphase
- Telophase
What is interphase and what occurs in interphase in
a) Nucleus
b) Cytoplasm
Preparatory events for mitosis NUCLEUS: - DNA Replication CYTOPLASM: - Centrosome duplication
What occurs in G1 of interphase?
The cell synthesizes mRNA and proteins (increases the amount of cytosol in the cell)
What is the importance of interphase?
Without the time to grow and carry out DNA replication during interphase, eukaryotic cells would be unable to successfully carry out cell division
What is the cell cycle composed of?
G1 phase, S phase, G2 phase and M phase
How is the cell cycle regulated?
Cell cycle is regulated at three checkpoints to ensure that the cells are ready to proceed through the process of division
At each of these checkpoints, the cell waits to receive signals on whether or not it has carried out the functions that should have been completed.If the cell receives the correct signals, it will allow itself to continue through the cell cycle, if not it either waits for the necessary tasks to be carried out or stops the cell cycle completely
What are the three key checkpoints of the cell cycle?
(G1) , (G2), (M)
When does the G1 Phase occur?
Right after cells have divided
What occurs in G2 Phase?
G2 phase is when the organelles of the cell need to duplicate.
What is the order of the phases?
G1, S, G2, M
What occurs in Prophase in
a) Nucleus
b) Cytoplasm
NUCLEUS:
- Sister Chromatids appear
CYTOPLASM:
- Early Spindle formation
What occurs in Pro-meta-phase in
a) Nucleus
b) Cytoplasm
NUCLEUS: - Membrane dissolves (Fragments remain) CYTOPLASM: - Microtubules extend - Attachment to Kinetochore
What occurs in Metaphase in
a) Nucleus
b) Cytoplasm
“NUCLEUS”:
- Attached chromosomes align on “Metaphase Plate”
CYTOPLASM:
- Extension of Spindle forms symmetry & plate formation
What occurs in Anaphase in
a) Nucleus
b) Cytoplasm
“NUCLEUS”: Separation of sister chromatids CYTOPLASM: De-polymerization of Microtubules & Migration of Chromatids
What occurs in Telophase in
a) Nucleus
b) Cytoplasm
“NUCLEUS”: Reformation of nuclear membrane (from remnants of old envelope) CYTOPLASM: Cytokinesis & Cleavage Dissolution of Spindle
After mitosis, what does each daughter cell have?
Each daughter cell:
- Correct chromosome number
- 1 centrosome
What does too much Profileration cause?
can form cancer (unregulated growth of cells)
What is it known as when a cell must die
APOPTOSIS, “Programmed Cell Death” - cells that are no longer needed or are a threat
What is the failure of the first two checkpoints (G1, G2/M) caused by?
Mostly occurs upon DNA damage
When does G1 checkpoint occur?
Before DNA Replication
What occurs if there is no progression signal in G1 checkpoint?
Cell Cyle Arrest -> G0 phase
Which checkpoint is the most important and why?
The G1 checkpoint is the most important because it is there where the cell “decides” whether or not to divide
What happens if a cell fails a checkpoint?
If the checkpoint mechanisms detect problems with the DNA, the cell cycle is halted and the cell attempts to either complete DNA replication or repair the damaged DNA
Which of the following is the simplest collection of matter that can live? tissue cell organ molecules
cell
A researcher wants to film the movement of chromosomes during cell division. Which type of microscope should she choose and why is it the best choice?
- light microscope, because of its high resolving power
- scanning electron microscope, because of its ability to visualize the surface of subcellular objects
- light microscope, because the specimen is alive
- transmission electron microscope, because of its high magnifying power
- transmission electron microscope, because of its high resolving power
light microscope, because the specimen is alive
Although the resolution of the light microscope is far less than that of electron microscopes, light microscopy is the only technique that permits one to observe living cells.
Why can’t an electron microscope be used to view living cells?
The beam of electrons used to illuminate a specimen also destroys the samples, meaning that electron microscopes can’t be used to image living cells.
Consider two cells with the same volume but with very different surface areas due to differences in their shapes. The cell with the larger surface area is likely to __________.
be involved in the rapid uptake of compounds from the cell’s environment
What limits the maximum size of a cell?
- the shape of the cell
- the cell’s surface-to-volume ratio
- the time it takes a molecule to diffuse across a cell
Which of the following structures is found in eukaryotic but NOT prokaryotic cells?
- mitochondria
- plasma membrane
- ribosomes
- cytosol
- DNA
Mitochondria, only eukaryotic cells have membrane-bound organelles such as mitochondria
A substance moving from outside the cell into the cytoplasm must pass through what?
Plasma membrane. The plasma membrane defines the boundary between the cytoplasm and the outside of the cell.
In terms of cellular function, what is the most important difference between prokaryotic and eukaryotic cells?
Eukaryotic cells are compartmentalized, which allows for specialization.
What features do prokaryotes and eukaryotes have in common?
Ribosomes, plasma membrane, and cytoplasm
A particular cell has a nucleus and chloroplasts in addition to the fundamental structures required by all cells. Based on this information, this cell could be
- a cell from a pine tree
- a photosynthetic protist cell or a plant cell
- a cell from the intestinal lining of a cow
- a bacterium
- a yeast (fungus) cell
-a photosynthetic protist cell or plant cell Some protists (such as algae) can photosynthesize, and so can plants. As both the protists and plants are eukaryotes, they contain organelles.
What is the functional connection between the nucleolus, nuclear pores, and the nuclear membrane?
Subunits of ribosomes are assembled in the nucleolus and pass through the nuclear membrane via the nuclear pores.
A dish of animal cells was grown in the presence of radioactive phosphorous. The phosphorous largely ended up in nucleotides inside the actively growing animal cells. In which cellular structure or structures would you predict the majority of the radioactive phosphorous to accumulate?
- the nucleus
- the Golgi apparatus
- rough endoplasmic reticulum
- rough endoplasmic reticulum and Golgi apparatus
- the Golgi apparatus and the nucleus
- nucleus
Large numbers of nucleotides would be used to make new DNA as the cells grew, and the DNA is housed in the nucleus.
Which of the following groups is primarily involved in synthesizing molecules needed by the cell?
smooth endoplasmic reticulum, ribosome, vacuole
- lysosome, vacuole, ribosome
- ribosome, rough endoplasmic reticulum, smooth endoplasmic reticulum
- vacuole, rough endoplasmic reticulum, smooth endoplasmic reticulum
- rough endoplasmic reticulum, lysosome, vacuole
-ribosome, rough endoplasmic reticulum, smooth endoplasmic reticulum
Each of these structures is capable of synthesizing molecules needed by cells (vacuole cant)
Which of the following categories best describes the function of the rough endoplasmic reticulum?
- information storage
- manufacturing
- energy processing
- breakdown of complex foods
- structural support of cells
-manufacturing
The rough endoplasmic reticulum is involved in the manufacture of proteins for the endomembrane system.
You would expect a cell with an extensive Golgi apparatus to __________.
move rapidly store large quantities of ions secrete large amounts of protein make large amounts of ATP absorb nutrients in the GI tract
The Golgi apparatus modifies and sorts the lipids and proteins produced in the ER. Cells that secrete large amounts of material require an extensive Golgi apparatus.
A researcher made an interesting observation about a protein made by the rough endoplasmic reticulum and eventually found in a cell’s plasma membrane. The protein in the plasma membrane was actually slightly different from the protein made in the ER. Where was the protein probably altered?
Golgi Appartatus
Vesicles carrying proteins from the rough ER fuse with the Golgi apparatus, where the proteins may be altered.
What is the flow of materials through the endomembrane system?
Rough ER +Smooth ER
The Golgi Apparatus (Cis then Trans)
Lysosome
Plasma Membrane
Which of the following sequences represents the order in which a protein made in the rough endoplasmic reticulum might move through the endomembrane system?
plasma membrane → nuclear envelope Golgi apparatus → mitochondria nuclear envelope → lysosome Golgi apparatus → lysosome lysosome → plasma membrane
Golgi apparatus → lysosome
Proteins of the endomembrane system are synthesized in the rough ER, modified and sorted in the Golgi, and then transported to other organelles of the endomembrane system such as vacuoles.
A protein that ultimately functions in the plasma membrane of a cell is most likely to have been synthesized where?
All of the membrane proteins of the endomembrane systems are made in the rough ER.
Which of the following five membranes is most likely to have a lipid composition that is distinct from those of the other four?
endoplasmic reticulum Golgi apparatus plasma membrane mitochondrial outer membrane lysosome membrane
mitochondrial outer membrane
The mitochondria are not part of the endomembrane system and must synthesize their own lipids.
Which of the following statements about chloroplasts and mitochondria is true?
Mitochondria, but not chloroplasts, contain a small amount of DNA.
Chloroplasts and mitochondria have three sets of membranes.
Chloroplasts and mitochondria are components of the endomembrane system.
Chloroplasts, but not mitochondria, are completely independent of the cell of which they are a part.
Chloroplasts and mitochondria synthesize some of their own proteins.
Chloroplasts and mitochondria synthesize some of their own proteins - because they contain DNA and ribosomes
Which type of cell is most likely to have the largest number of mitochondria?
- bacterial cells that are growing on sugars
- photosynthetic cells in the leaves of a tree
- muscle cells in the legs of a marathon runner
- inactive yeast cells that are stored for future use
- nondividing cells in the skin on your finger
Cellular respiration releases energy that cells need in order to carry out their functions. Active muscle cells need large amounts of energy.
Where are the ribosomes of mitochondria found?
The ribosomes in the mitochondria are found in the matrix of the mitochondria, not in the intermembrane space
Which of the following organelles might be found inside other organelles?
mitochondria transport vesicles the nucleolus ribosomes No organelles are found inside of other organelles.
ribosomes
Ribosomes are nonmembranous organelles that are found in the cytoplasm but also in mitochondria and chloroplasts.
Microtubules and microfilaments commonly work with what to perform many of their functions?
Golgi Apparatus
Which of the following structures is found in animal cells but NOT in plant cells?
mitochondria rough endoplasmic reticulum plasma membrane Golgi apparatus centrioles
-centrioles
Although plant cells have a microtubule organizing center, they lack a pair of centrioles.
Cilia and flagella move due to the interaction of the cytoskeleton with what?
Motor proteins, such as dynein, use energy to move parts of the cytoskeleton.
What is a a common characteristic of a plant cell wall and an animal cell extracellular matrix?
Both plant cell walls and the ECM of animal cells allow movement of water and small solutes.
The plasma membrane is referred to as a “fluid mosaic” structure. Why?
The fluid aspect of the membrane is due to the lateral and rotational movement of phospholipids, and embedded proteins account for the mosaic aspect.
Consider the currently accepted fluid mosaic model of the plasma membrane. Where in the plasma membrane would cholesterol most likely be found?
in the interior of the membrane
in the interior and on the inside surface, but not on the outside surface
on the outside (external) surface of the membrane
on the inside (cytoplasmic) surface
on either surface of the membrane, but not in the interior of the membrane
interior of the membrane
The steroid cholesterol, wedged between phospholipid molecules in the plasma membranes of animals, helps stabilize the membrane.
What is meiosis?
a type of cell division that results in four daughter cells each with half the number of chromosomes of the parent cell
Meiosis I
PMAT I: The first cell division of meiosis when the homologous pairs are split up into two separate cells.
Meiosis II
PMAT II: The second cell division of meiosis. This is when the sister chromatids are split up into two separate cells.
Does DNA replication occur in meiosis 1 or 2?
Meiosis II :No DNA replication during this division
Meiosis I :There IS DNA replication during this division
What is The Mitotic Spindle?
A structure composed of microtubules which segregates chromosomes into the daughter cells during mitosis.
What is the centosome?
They are made from two centrioles. the centrosome is an organelle that is the main place where cell microtubules are organized (MTOC – Micro-Tubule Organizing Center)
What are the functions of the centrosome?
The main purpose of a centrosome is to organize microtubules and provide structure for the cell, as well as work to pull chromatids apart during cell division.
What is a centriole?
a centriole is a cylindrical cellular organelle composed mainly of a protein called tubulin
What are the functions of centrioles?
The centrioles help in the formation of the spindle fibers that separate the chromosomes during cell division (mitosis)
Describe the centrosome cycle
- 2 subunits of 1 centriole exist “perpendicular” – held by linkages
- They Move apart & new centriole microtubules begin to get laid down perpendicularly
- Old linkages break -> 2 centrioles (with 2 subunits @ 90*)
- Oppose each other & migration to opposite poles begins….
Describe the Spindle Formation
- Microtubule proteins form from the CENTROSOME & extend into cytoplasm
- More “tubulin” subunits added on -> Expansion of the Microtubules
- Short Microtubules – “Aster”
- Longer Microtubules – “Spindle Microtubules”
What are the short spindle fibres (microtubules) known as?
Short Microtubules – “Aster”
What are the long spindle fibres (microtubules) known as?
Longer Microtubules – “Spindle Microtubules”
Why is the spindle fiber necessary?
The spindle is necessary to equally divide the chromosomes in a parental cell into two daughter cells
What is the kinetochore?
The kinetochore forms in eukaryotes, assembles on the centromere and links the chromosome to microtubule polymers from the mitotic spindle during mitosis and meiosis
Seperation in mitosis is assisted by what enzyme?
Enzyme assisted “Separase” – breaks down connections btw sister chromatids
Describe the seperation during mitosis
- Sister Chromatids migrate away
- Moving along kinetochore microtubules – toward centriole,
- Move along the network
- Kinetochores shorten – depolymerization, Chromatids move on as they do
Describe the division of the cytoplasm in cytokinesis
Opposing Centrosomes give “Polarity”
- Short “Aster” microtubules give push in opposite direction – away from centre
- Before separation, “Non-kinetochore microtubules” play important role;
- > Elongating the cytoplasm by extending in opposing directions
What is the cleavage furrow?
the cleavage furrow is the indentation of the cell’s surface that begins the progression of cleavage, by which animal and some algal cells undergo cytokinesis, the final splitting of the membrane, in the process of cell division. In a typical animal mitosis, a cleavage furrow forms at the equatorial cortex after anaphase. This furrow then advances inwards to separate the two daughter cells.
What does each chromosome contain?
Each chromosome contains one long DNA molecule associated with many proteins.
How can a protein outside the cell cause events to happen inside the cell?
A protein outside the cell can bind to a receptor protein on the cell surface, causing it to change shape and sending a signal inside the cell
What effect does phosphorylating a protein have on that protein?
Protein phosphorylation causes a shape change in the phosphorylated protein. The shape change results from the interaction of the newly added phosphate groups with charged or polar amino acids on the protein being phosphorylated. The shape change alters the function of the protein, most often activating it, but in some cases phosphorylation instead decreases the activity of the protein.
What is the function of the mitotic cell cycle?
To produce daughter cells that are genetically identical to the parent cell (assuming no mutation has occurred)
When are sister chromatids created?
When DNA is replicated, during S-phase.
When are sister chromatids seperated?
Sister chromatids are separated during mitosis prior to cytokinesis.
Which of the following is FALSE regarding sister chromatids?
a) Sister chromatids are created when DNA is replicated.
b) Both of the sister chromatids end up in the same daughter cell after cytokinesis has occurred.
c) Sister chromatids are separated during mitosis.
d) Sister chromatids form in the S-phase stage of the cell cycle.
e) Sister chromatids are attached to one another at the centromere.
b) Both of the sister chromatids end up in the same daughter cell after cytokinesis has occurred.
This statement is false. Each of the sisters ends up in a different cell after cell division.
