Lect Chapter 3c and d Flashcards
What is another name for the cytoplasm and what is a composed of?
A.k.a. protoplast
1 - cytosol
2 - inclusions
3 - organelles
What is the cytosol, inclusion, organelles?
- Cytosol Gel like solution made up of water and soluble molecules
- inclusions insoluble molecules
- organelles metabolic machinery structure of cell
Two classes of cytoplasmic organelles are?
Members and nonmembers
Name the membranous organelles
Mitochondria endoplasmic reticulum Golgi apparatus peroxisomes lysosomes
Nonmembers cytoplasmic organelles are?
Ribosomes
cytoskeleton
centrioles
Membranous organelle in the cytoplasm resembles bacteria? Explain its main function and it’s unique membrane?
- Mitochondria has a double membrane, the innermembrane has many folds called Cristae
- it’s main function is to produce most of the cells energy molecules ( ATP)
What cytoplasmic organelle has its own DNA, RNA and ribosomes?
Mitochondria have mDNA, mRNA, and ribosomes
Where are ribosomes located And what are their differing functions?
What are they made it up of?
- Ribosomes are made of proteins and ribosomal RNA ( rRNA)
- Free ribosomes are free-floating and they make the protein used in the cell
- membrane-bound ribosomes are attached to the membrane of the endoplasmic reticulum (ER) and make protein for membranes of lysosomes Export out of the cell (for use out of the cell)
What is another name for endoplasmic reticulum (ER), what are the two types, And describe them?
A.k.a. cisternae - two types: Rough ER smooth ER - Consist of a series of parallel interconnected cisterns or flattened membrane is tubes that enclose fluid filled interiors.
What’s the Visual difference Between rough ER and smooth ER?
Rough ER has ribosomes smooth ER has none
Explain rough ER function
- ribosomes on the rough ER help with protein synthesis
- proteins enter cisterns and are synthesized/modified as they go through the fluid filled tubes
- Final Protein is enclosed in a vesicle and sent to Golgi apparatus for further processing
Explain smooth ER function
- continuous with rough ER these looped tubes have enzymes (integral proteins)
- lipid metabolism (cholesterol, hormones)
- absorption, synthesis, and transport of fats
- detoxification of certain chemicals (drugs , Pesticides)
- Convert glycogen to Free glucose
- stores and release calcium
Describe the Golgi apparatus?
Stacked flattened membranous cistern sacs
What is the post office or the traffic director of the cell? And how does it do this?
- Golgi apparatus
- it modifies, concentrates, and packages proteins and lipids received from rough ER
Three steps involved in Golgi apparatus delivery system
1 - Transport vesicles coming from ER fuse with cis face (inner or closer to nucleus) of Golgi
2 - proteins or lipids are further modified sorted and packaged
3 - Final product is sent to one of three pathways in new transport vesicles coming off of trans face (outer or further from nucleus)
What are the three pathways the Golgi apparatus can send the final transport vesicles to?
Pathway:
A. Secretory vesicles containing proteins for exocytosis fuse to plasma membrane ejecting them for use outside of the cell
B. Vesicles containing lipids or transmembrane proteins fused with plasma membrane or organelle membrane deposit in contents directly into destination membrane
C. Lysosomes containing digestive enzymes remain in the cell holding contents until needed
Describe The membranous cell organelle peroxisomes.
What is its function?
- Membranous sacs containing powerful detoxifying substances
- remove free radicals
- Play a role in the breakdown and synthesis of fatty acids
What are the two main detoxifiers in peroxisome‘s and how do they work
- oxidase uses oxygen to convert toxins into hydrogen peroxide
- Catalase converts hydrogen peroxide to water
Describe lysosome shape.
What is its function?
- spherical membranous bags
- isolates potentially harmful intracellular digestion from the rest of the cell ( CF site)
- Digest ingested bacteria viruses and toxins with digestive enzyme acid hydrolases
- Degrade non-functional organelles
- autolysis-injured cell releases intracellularly causing the cell to digest itself.
- metabolism-breaks down and releases glycogen breaks down and releases calcium ion from the bone
What is the Endomembrane system composed of?
Composed of the
- ER
- Golgi apparatus
- secretory vesicles
- lysosomes
What do you things does the Endo membrane system mostly due?
- Produce, degrade, store, and export biological molecules
2. Degrade potentially harmful substances
What is The non-memraneous cytoskeleton?
- network of rods that run Throughout cytosol
- Hundreds of types of proteins Link rods two other cell structures
- acts as the cells bones, ligaments and muscles by playing a role in the movement of cell components.
What are three types of cytoskeleton?
Microfilaments
Intermediate filaments
Microtubules
Describe the microfilaments and their role
- Made of semiflexible strands of joined spherical protein subunits (actin)
- The strands are arranged in a web attached to cytoplasmic side of plasma membrane which strengthened cell surface and helps resist compression
- Some r involved in cell motility, changes in cell shape, or endocytosis and exocytosis.
Describe intermediate filaments size, construction, and purpose.
- size is in between microfilaments and microtubules
- made of tough insoluble rope like protein fibers made of tetramer (four) fibrils
- help cell resist pulling forces and act as internal guy wires attached to desmosome plaques.
- named differently in different cells
Describe microtubules composition, size and function
- composed of protein subunits (tubulins) that forms hollow tubes.
- largest of cytoskeleton elements
- radiate from centrosome area of cell
- determines overall shape of cell and distribution of organelles
- many organelles or tethered to make it to microtubules keeping them in place
- microtubules are used as tracks by motor proteins
What are motor proteins function how is it done?
–Function in movement of organelles and other substances around the cell
- powered by ATP
- use microtubules as tracks
Where is the centrosome (cell center) located?
What’s the main function? What’s it made of describe its shape?
- located near the nucleus
- It is a microtubule organizing center, made of granular matrix and centrioles.
What are centrioles and how are they arranged?
What do they form the basis of?
What are two Things they could do?
–They are a pair of barrel shaped microtubular organelles that light at Right angles to each other
- barrel is arranged in nine triplet tubules 9+0
- They form the basis of cilia and flagella
- Aid in cell division
- Form cytoskeletal track system
What are three cellular extensions and what’s their purpose?
- Cilia and flagella aid in the movement of the cell or of materials across the surface of the cell
- Microvilli are fingerlike projections that increase surface area
Describe cilia, And what’s the function?
Celia are whip like moving extensions on surfaces of some cells that work together in a sweeping motion to move substances across the cell surface in one direction
Describe flagella and their function
Flagella or longer extensions that propel the whole cell.
swimming movement example tail of sperm
Explain the cilia movements
Alternate between power stroke and recovery stroke which produces a current at cell surface that moves substances forward
What is the structure of Cillian flagella
Made by centrioles they consist of microtubules that have nine sets of doublets surrounding A central pair of doublets 9+2 pattern of microtubules
What are microvilli? What are they used for? What is the structure
Minute fingerlike extensions of plasma membrane projecting from the surface
- used to increase surface area for absorption
- have a core of actin microfilaments that is used for stiffening of projections
What is the nucleus of the cell?
- Largest organelle, contains genetic library of blueprints for synthesis of nearly all cellular proteins
What is a cell called with one, many, no nucleus?
- uni nucleated
- Multi nucleated
- Anucleated
What. Are the three main structures of the nucleus?
- Nuclear envelope
- Nucleoli
- Chromatin
What is the structure of the nuclear envelope? And explain the function
- It has a double membrane barrier - outer layer is continuous with rough ER and studded with ribosomes
- Inner layer called nuclear lamina has a network of mesh proteins that maintains nuclear shape and acts as scaffolding for DNA.
- nuclear pores allows substances to pass in and out of the nucleus but guarded by nuclear pore complex regulating transport of specific large molecules
What is the structure of nucleoli?What did they do? How many usually Per cell?
Dark staining spherical bodies with in the nucleus that are involved in ribosomal RNA (rRNA)synthesis ribosome subunits assembly.
One or two per cell
What is chromatin? Where is it found? What is the percentage composition?
- It is part protein part DNA
- found in the nuclear plasm
- consist of 30% strands of DNA 60% histone proteins and 10% RNA
How is chromatin arranged?
Arranged in Fundamental units called nucleosome’s made of DNA wrapped around histones
What are chromosomes?
They are condensed chromatin. Condensed to protect fragile chromatin threads during cell division
What is the cell cycle and what are the two major periods of the cell cycle?
– Series of changes A cell undergoes from the time it is formed until it reproduces
- Two major periods are the interphase and cell division
What is the interphase and what is the cell division also called?
- interphase is where the cell grows and carries on its usual activities
- mitotic phase is when the cell divides into two
What are the sub phases of interphase?
- G1 ( gap one): growth and metabolism
(Once it grows to a certain size it triggers a G1 restriction point moving it to the next subfees) - S (synthetic): DNA replication (DNA synthesis phase)
- G2 Open parentheses gap two): growth and preparation for division
Explain The DNA replication (DNA synthesis phase) phase in interphase.
- Double strand DNA Helices unwind and unzip:
- Replication fork: point where strand separate
- replication bubble: active area of replication
- each strand is a template for a new complementary strand - Irony starts replication while laying down short strands that act as primer
- Do you need polymerase attaches to primer and begins adding nucleotides to form a new strand
- in a polymerase synthesizes both new strands at the same time (one leading and one lagging) - DNA polymerase works only in one direction, leading strand is synthesized continuously lagging strand is synthesized into segments
- DNA ligase splices the lagging strand segments together
- Two identical daughter DNA molecules are formed from original
Why is DNA replication called semi conservative?
Because each new double-stranded DNA is made of one old strand and one new strand
In the mitotic phase of cell division what are the two distinct events?
- Mitosis
2. Cytokinesis
What are the four stages of mitosis that ensure each cell receive a full copy of replicated DNA?
PMAT
Prophase metaphase anaphase telophase PMAT
What are the two parts that prophase can be broken into and what occurs during each?
- Early prophase
- chromatin condenses to chromosomes
- each chromosome and it’s duplicate sister chromatid (DNA) are held together by centromere
- centrosome and it’s duplicate begin synthesizing microtubules pushing each centrosome to opposite poles of cell. (Mitotic spindle) other microtubules called Astors radiate from centrosome. - Late prophase
- nuclear envelope breaks up
- special microtubules attached to specific area on centromere is called kinetochore and Paul chromosomes to center (equator) of the cell
- non-kinetochore microtubules push against each other, causing poles of cell to move further apart
What happens during the metaphase of cell division?
- centromere‘s of chromosomes are precisely a line at cells equator
- Metaphase plate or imaginary plane midway between poles is visible
What happens in anaphase of cell division?
- centromere’s of chromosomes split simultaneously and each chromatid now becomes a separate chromosomes
- One chromosome of each original pair goes to opposite poles via motor proteins of kinetochores
- nonkinetochores microtubules keep forcing poles apart
- shortest of all phases
What happens during the Tele phase of cell division?
- begins when chromosome movement stops
- each set of chromosomes (Opposite ends of the cell) uncoil’s to form chromatin
- New nuclear membranes form around each chromatin mass
- nucleoli reappear
- spindle disappears (At center equator)
What occurs during cytokinesis? And when does it happen?
- ring of actin microfilaments contract to form cleavage furrow
- two daughter cells are pinched apart
- Starts during late anaphase and continues through mitosis
What are the go and stop signals the direct cell to divide?
- go signals include growth factors, hormones. Surface to volume ratio of a cell (cell grows too big) becomes in adequate for exchange
- stop signals include contact inhibition, when they come into contact with other cells
What are the two proteins crucial to a cell’s ability to accomplish the S phase and enter mitosis? How did they interact with each other?
Cyclin and CDKS (cyclin – dependent kinases)
- CDKS activates cyclins when they bind to them
- cyclin-CDKS complex then activates enzyme Cascades that prepare cell for division.
- cyclins Or destroyed after my ptotic cell division, and process begins again
What are the checkpoints, what do they check for and What happens if they fail?
G1 checkpoint checks the cell division processes. If it’s faulty cell division stops until repairs are made. One stop it enters G0 no further division occurs.
G2/M checkpoint does the same
What is the master blueprints that holds theCode for proteins synthesis.
DNA, directs the order of amino acids in a polypeptide. The segment of DNA that holds the code for one polypeptide is referred to as a gene. Example GCC GGG GGC etc.
What determines the code and what does it consist of?
The code is determined by the specific order of nitrogen bases. It consist of three sequential bases triplet code. Each triplet specifies the code for a particular amino acid
