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What is the goal of the cell cycle/ life cycle?
For the cell to divide into two daughter cells
What are the four processes of cell cycle?
Cell growth
DNA replication
Chromosomes in daughter cells
cell division
What is the biggest part of the cell cycle for bacteria?
Cell growth and DNA replication
How does the cell cycle in prokaryotic organisms happen?
The chromosomes are distributed through binary fission?
What are the three phases of bacterial cell cycle?
B period: end of cell division to DNA replication
C period: the time the chromosomes assemble
D period: time after chromosome replication and end of cell cycle
What is the process by which eukaryotes split?
Mitosis( evolution of binary fission)
Which is the biggest phase of cell cycle in bacteria? B phase, C phase or D phase
C period
Where does bacterial chromosomal replication start? (a specific site)
A site called The origin of replication in the middle of a cell.
how they work: the replication start and go on opposite ends by catalysts. The origins go to different poles to pull chromosomes in app direction. The plasma membrane grows apart.
What are the four phases of mitosis ?
G1 phase(growth)
S phase(synthesis)
G2 phase( gap 2 or growth 2)
M phase ( mitosis and cytokinesis)
What is interphase?
End of mitosis all the way to the beginning of mitosis
what are chromosomes?
They are nuclear units of genetic information that are divided and distributed during mitosis
chroma = colour (describing their strong staining by particular dyes)
soma = body
What are chromatids?
The replication of the DNA chromatids
It represents two identical molecules sister chromatids
What is a chromatid?
A small portion of DNA composed of
How do we define the number of chromosomes in a species?
By ploidy number
Diploid(2n): humains have 23 pairs of chromosomes, 46 in total . Half from one type(mom) and other from dad. Called homologue pais
Haploid(1n): gametes. Only have one copy of chromosomes of the same type
What is the longest phase of the cell cycle for eukaryotic cells?
Interphase
What happens in the G1 phase?
Cell caries its functions, grows. prepares ribosomes and enzymes. The DNA is not duplicated yet
What happened in the S phase?
DNA replication and chromosome duplication
What happens in G2 phase?
Cell growth continues and prep for mitosis. The DNA has replicated already.
Describe G0 phase?
Also called quiescence. Its a rest phase where it stops dividing
What are the five stages of Mitosis?
Prophase
Prometaphase
Metaphase
Anaphase
Telophase
What is this structure ( purple strings) ? What is its function ?
Spindle: It’s a structure of proteins and microtubules that forms during cell division that separates the sister chromatids
What is this structure (yellow)? What is its function ?
Centromere: region not an actual structure) in the middle of a chromosome where the spindles attach
What is this structure (yellow)? What is its function ?
Centrosome: organizes the microtubule cytoskeleton and positions organelles. It’s a pair of microtubules
What is the function of a kinetochore ?
Kinetochore: a large protein that connects chromosomes to the spindle fibers/microtubules. It is in the center of the chromosomes in the outside area.
Binds the centromere and chromosomes together
What is the structure of cleavage furrow? What is its function ?
It’s a contractile ring formed by microfilaments
What is the structure of cell plate? What is its function ?
It is made from cell wall and cell membrane components brought during telophase in plant cells.
What’s the different between animal cells and plant cells in cytokinesis
Animal cells:the cleavage furrow is a contractile ring formed by microfilaments
Plant cells: vesicles for a cell plate within the cell to form a cell plate. A new cell wall forms and THEN, the membrane separates the new daughter cells
What can be stored in plant cells vacuoles?
Plastids/ pigments
nutrients
water
What is the longest phase of the cell cycle?
Interphase
Explain supercoiling
Histones: proteins in packs of four that DNA wraps around
Nucleosomes: 4 histones units wrapped by DNA
Chromatin: 8 nucleosomes
Chromosomes: chromatids chilled together
What’s the structure of DNA?
Double stranded helix
What happens in prophase? CC,x2, ½,s
Chromosomes condense( become visible in microscope)
Chromosomes are doubled (after G2)
Centrosomes divide in two parts (go opp of cell)
Spindles form
What happens in prometaphase?
Nuclear envelope breaks down!
Microtubules form complete spindles
Microtubules attach to kinetochores
How do spindles form and connect to chromosomes?
Microtubules extend from the centriole to form the spindle apparatus
What happens in Metaphase?
Spindles are fully fledged
Metaphase=middle: chromosomes align in the middle of the cell
Sister chromatids are held by two opp forces: kinetochores out and cohesins(protein complex) in
What happens during Anaphase?
seperase proteins splits the sister chromatids
spindles (myosin) bring chromatids to opposite poles
What happens during Telophase?
Chromosomes decondense
A new nuclear envelope forms around chromosomes (we still only have one cell!!!)
The cytoplasm divides by furrowing
Which of the following is not part of mitosis?
Anaphase
Cytokinesis
Prometaphase
Telophase
Metaphase
Anaphase
Cytokinesis
Prometaphase
Telophase
Metaphase
How do bacteria undergo cell division?
A pilus (surface of bacteria) leaves its body and enters the other’s membrane containing some genetic material (horizontal gene transfer)
Why would cells undergo cell division?
For cell development
Cell growth (natural)
Repair of organism
Need to compete external source
Microscopy
The use of microscopes to visualize and study small objects or organisms.
Magnification
The process of enlarging the apparent size of an object in microscopy.
Resolution
The ability to distinguish between two closely spaced objects in microscopy.
Cytosol
The fluid portion of the cytoplasm, excluding organelles.
Cytoplasm
The contents of a cell, including the cytosol and organelles.
Organelle
A specialized structure within a cell that performs specific functions.
Light microscopy
The use of visible light to magnify and observe specimens.
Electron microscopy
The use of a beam of electrons to magnify and observe specimens with higher resolution than light microscopy. This includes SEMs and TEMs
Antonie van Leeuwenhoek
A scientist who was one of the first people to observe microorganisms using a microscope of his own design, making important contributions to biology.
Magnification
The ratio of the object as viewed to its real size.
Resolution
The minimum distance that two points in the specimen can be separated and still be seen as two points, depends primarily on the wavelength of light or electrons used to illuminate the specimen.
Light microscopes
Microscopes that use light to illuminate the specimen, including : bright field microscopy, fluorescence microscopy, and confocal microscopy.
TEM (Transmission Electron Microscopy)
A type of electron microscopy that involves rays transmitted through thin inTernal sections made using a microtome, with black objects on a white background.
SEM (Scanning Electron Microscopy)
A type of electron microscopy that involves rays scanned over the surface of a specimen
What are the two types of light microscopes?
Fluorescence Microscopy
Confocal Laser Scanning Microscopy
Explain Fluorescence Microscopy
A molecule in the specimen absorbs a particular wavelength of light and emits some of that light into another wavelength. Observed on a black back background.
Specific dyes used to label specific molecules
Explain Confocal Laser Scanning Microscopy
It focuses a laser light source onto a very thin plane. The specimens then emit a fluorescent light.
Used to examine thick specimens in 3D images
What is biology?
From the Greek —-Bios=life and logy=study.
What is an organism?
An assembly of molecules that function as a whole that exhibit life
Ex:
A tree absorbs sunlight through its leaves, converts it into energy through photosynthesis, and grows by producing new branches and leaves.
How many types of organisms are there? What are they?
Two:
Unicellular organisms
Multicellular organisms
What are the three postulates of Cell Theory?
All organisms are composed of one or more cells
The cell is the basic structural and functional unit of al living organisms
Cells arise only from the division of pre-existing cells
Robert Hooke, 1665
English scientist who defined the term "cell" and made significant contributions to the field of microscopy.
What is essential to life?
Energy
• For living cells, energy is required to build complexe things (proteins)
Why was the invention of the microscope crucial to biology?
Allowed scientist to understand how living organisms were built from cells
What are the different cell types?
Prokaryotic cells
Eukaryotic cells
What is a prokaryotic cell?
A cell with no nucleus
Name features of a prokaryotic cell
No nucleus (NUCLEOID)
No organelles
Small (micrometer)
Hopanoids
Usually spherical,rodlike and spiral
What is an eukaryotic cell
A cell with a nucleus ( central space with all the DNA)
Name features of an eukaryotic cell
Has a nucleus
Has specific organelles that carry out basic fns of life
Large (10-20 micrometers)
Sterols
What is COGRASHE?
C-made up of one ore more cells
O- displays organisation
G- grows and develops
R- reproduces
A- adapts
S- responds to stimuli
H- homeostasis
E- requires energy
What are the four essential elements to all living cells?
Plasma membrane
Cytoplasm
Chromosomes
Ribosomes
What is the structure of the plasma membrane?
It is made of a bilayer of phospholipid molecules.
The molecule contains:
a hydrophilic head( polar )
a hydrophobic tail(non-polar)unsaturated+ saturated
What is the function of the plasma membrane?
It controls the flow of substances of the cell. That is essential for maintaining the internal environment.
Where and what does the cytoplasm do?
It’s below the plasma membrane within the cell. It is a fluid that cates and environment for cell processes.
What is the cytosol?
It’s the aqueous part of the cytoplasm where DNA synthesis
What is the cytoskeleton?
It’s a network of fibers throughout the cytoplasm
maintain the cell’s shape
organize cell’s activity and structure
fixes many organelles
chromosome segregation during cell division
Which domains consists of prokaryotic cells?
Bacteria
Archaea/mue bacteria
Which kingdoms make up the domain eukariya?
Animals
Plants
Fungi
Protista
Bacteria and archaea are ____________ distinct.
Bacteria and archaea are evolutionary distinct
What are some structural organelles present in plant cells but not animal cells?
Chloroplasts
Central vacuole
Cell wall
Plasmodesmata
What is the definition of an organelle?
A structure surrounded by a membrane
Describe the structure of a prokaryotic cell
Rigid cell wall (capsule) made of gycocalyx
Plasma membrane
Use flagella or pills for locomotion
How do bacterial plasmids differ in comparison to other organelles?
They contain an extrachromosomal DNA that replicate independently
What does the plasma membrane do in prokaryotic cells?
Metabolizes food into energy ( mitochondria in eukaryotes)
What does the cell wall do in prokaryotic cells?
It covers and hides the cell from external organisms
What does the mitochondria do in eukaryotic cells?
Site for cellular respiration/energy production
IT IS AN INDEPENDANT ORGANELLE FROM THE CELL
What are some structural organelles present in animal cells but not plant cells?
Lysosomes
Centrioles
*Flagella
Label the following structures on the drawing:
Nuclear envelope
Nuclear pores
Nucleolus
Chromatin
Rough ER
Ribosomes
What is the nuclear envelope?
It encompasses the nucleus region and made up of two lipid bilayers
What are the nuclear pores?
It’s perforation through the nuclear envelope forming channels that regulate the transport of molecules between nucleus and cytoplasm
What is the nucleolus?
Distinct middle area of the nucleus that assembles ribosomes
What is the nuclear lamina?
It’s a dense fibre network of intermediate filaments
Where is a particularity of the ribosomes?
They are not considered an organelle
What are ribosomes made up of?What is their structure?
rRNA + proteins
They have two subunits:Large subunit (top) and small (bottom)
What is the role of ribosomes?
The site for protein synthesis: by decoding mRNA and forming polypeptide chains
Where are the ribosomes located?
Outside the Rough ER/ on nuclear envelope (bound)
In the cytosol (free)
Where is the site of photosynthesis in plant cells?
Chloroplast: use solar energy to produce food (sugar)
What are peroxisomes?
They are organelles (single membrane) which produce H2O2 to change into H2O. Oxidizes it
What are the two membranes called in the mitochondria?
Smooth outer membrane
Inner membrane (cristae) looks like folds
Note
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