4.1-4.9 Flashcards
What are the two important factors in microscopy?
Magnification and resolution.
How do light microscopes work?
Light passes through the organism, and lenses bend it to be magnified. Max about 1000X times. Detail up to 0.2 micrometers (smallest bacteria)
Classic example of resolution?
One star becoming two stars w/ higher resolution.
Define cell theory
1665-1900s, development of our understanding of the cell using light microscopes.
What is an electron microscope?
EM, 1950s. Beams electrons through specimens. Detail up to two nanometers (100X better than LM).
What are the two types of electron microscopes?
Scanning (SEM) and Transmission (TEM). Both use lenses to bend the paths of electrons.
SEM?
Used for detail in cell surface. Electron beam touches surface covered in gold foil (excites electrons). 3D, topographical images.
TEM?
Used for details of internal cell structure. Electron beam on thin slice of specimen, which also has heavy metals in it, attracting certain organelles.
What are the downsides of EM?
Kill the cell.
Other microscopy techniques?
Differential interference contrast, fluorescent stains.
Type of microscope used for: human hair, the surface details of white blood cells, organelle in the liver
LM, SEM, TEM
What must cells be large enough to hold?
DNA, protein and structures to survive and reproduce.
Why do cells need so much surface area?
fluid membrane, allows for the most access (see blocks example, pg. 54).
In 4.2, there is a review of phospholipid bilayer.
Two types of cells?
prokaryotes and eukaryotes.
Kingdoms that are prokaryotes?
Archaea and Bacteria
Eukaryotic kingdoms?
Fungi, animalia, protista, plantae
Diff. btw eukaryotes and prokaryotes?
Membrane-bound nucleus and organelles.
Things shared between eukaryotes and prokaryotes?
Interior of cells filled with cytosol, have chromosomes, have ribosomes, inside of the cell is cytoplasm.
Define cytosol
Thick, jellylike fluid inside a cell.
Define chromosome
Made up of genes, which are made up of DNA.
Ribosome function?
tiny structures that make proteins based on instruction from DNA.
Define cytoplasm
Everything and anything within a cell. (*Eukaryotes: only between nucleus and plasma membrane)
What are different things found in prokaryotic cells?
Fimbriae (sometimes- small things on the surface that can attach to others), ribosomes (diff. from eukaryotic ribosomes), nucleoid (where DNA is found-NO nucleus), plasma membrane, cell wall (!!), capsule (jelly-like outer coating), flagella (tails that move the cell).
How are some of the ways medicine responds to bacteria.
Because ribosomes are different in prokaryotes, medicine can stop protein synthesis in only them. Cell walls are chemically complex and protect bacteria, penicillin stops the growth of that wall.
How small is a pro cell compared to a eu cell, on average.
1/10.
Why are many diagrams of cells inaccurate?
They don’t include enough organelles– there can be millions of ribosomes.
What are all organelles bounded by?
lipid/protein membrane.
Describe the first basic functional group of the cell.
Nucleus and ribosomes: carry out the genetic control of the cell.
Describe the second basic functional group of the cell.
The endoplasmic reticulum, Golgi apparatus, lysosomes, vacuoles and peroxisomes are involved in the manufacturing, distribution and breakdown of molecules.
Describe the third basic functional group of the cell.
Mitochondria (animals) and chloroplasts (plants) process energy.
Describe the fourth basic functional group of the cell.
The cytoskeleton, plasma membrane, cell wall (ONLY plant) are used for structural support, movement and communication between cells.
What is cellular metabolism
chemical activities of a cell.
What do plant cells have that animal cells do not?
Chloroplasts and cell walls, central vacuole for holding water.
If a plant cell has a cellulose cell wall, how do molecules access the plasma membrane.
Channels called plasmodesmata (singular: plasmodesma)
What is the chloroplast responsible for
photosynthesis.
What is the cytoskeleton?
Structural support composed of fibrous proteins; provide for support and movement.
What do the fluid-filled spaces in organelles do?
Responsible for catabolizing or anabolizing molecules.
What are cell’s activities controlled by?
protein synthesis.
How many chromosomes make up human DNA?
46 (2m long, coiled up in nucleus).
The complex of proteins and DNA inside the nucleus is called…
chromatin. Looks like a diffuse/gradient mass.
What encloses the nucleus?
nuclear envelope
What is the nuclear envelope?
TWO phospholipid bilayers, protein lined pores (to allow/constrain entrance to large molecules, etc), which connect with endoplasmic reticulum.
What is the nucleolus?
A place in the nucleus where ribosomal RNA (rRNA) is synthesized to make parts of ribosomes. When they exit through pores, they become ribosomes.
What is mRNA?
(messenger), transcription of instructions for protein-synthesis genes in DNA, sent to cytoplasm, where ribosomes make proteins.
What are the processes that occur in the nucleus?
DNA is copied and passed on to daughter cells in cell division; rRNA is made and ribosomal subunits assembled; protein-making instructions in DNA are transcribed to mRNA.
what does a ribosome do?
builds proteins from mRNA.
Where are the two places where ribosomes are found?
Free ribosomes in cytosol, bound ribosomes attached to outside of endoplasmic reticulum or nuclear envelope.Each can move where it is.
What do the/ where do the proteins that are made from bound ribosomes go?
inserted in membranes, packaged in certain organelles, and exported from the cell.
What do the/ where do the proteins that are made from free ribosomes go?
many make enzymes that help with cellular respiration.
What does the ribosome making a protein look like?
pg. 59. nucleotide sequence of mRNA is transferred into a polypeptide sequence.
What role do ribosomes play in carrying out the genetic instructions of the cell?
Ribosomes synthesize proteins according to the instructions of mRNA, which was transcribed from DNA in the nucleus.
What make up the endomembrane system?
Endoplasmic reticulum, nuclear envelope, Golgi apparatus, lysosomes, vacuoles, peroxisomes, plasma membrane.
Internal membranes are involved in most of a cell’s functions (hence ENDOmembrane system). What are these functions?
synthesis, distribution, storage and export of molecules.
How are membranes connected?
vesicles (membrane sacs), transfer membrane segments.
Largest component of EM system
ER: endoplasmic reticulum (a little net within cytoplasm).
What is the ER made of?
sacs and tubules, connected to/continuous with nuclear envelope.
Important function of EM system?
Dividing a cell into functional compartments.
Difference between rough and smooth ERs?
Has ribosomes, does not.
What does the smooth ER do?
Enzymes inside synthesize all types of lipids (sex hormones made in ER in ovaries, etc). In liver, enzymes in smooth ER detoxify alcohol, drugs, etc (this, however, increases tolerance to the drug and other similar drugs). Stores calcium ions until they need to make a muscle move in the cytosol.
What does the rough ER do?
Secretes proteins (ex. insulin).
The making of glycoproteins: ribosome creates a polypeptide chain, which enters into the ER, where it fold itself. It then attaches to glucose molecules (glycoprotein). When done, it is moved to a vesicle which removes it from ER.
The ER is capable of making its own mosaic membrane, because it can make lipids and proteins. The rough ER membrane will grow, and send part of it off to other parts of the cell in transport vesicles.
Explain why it is said that the endoplasmic reticulum is a biosynthetic workshop.
The ER produces a huge variety of molecules, including phospholipids for cell membranes, steroid hormones, and proteins (through bound ribosomes) for membranes , other organelles, and secretion by the cell.
Where to transport vesicles go after leaving the ER?
Golgi apparatus.
A Golgi apparatus is made up of _____ stacks
many-100.
What is the function of Golgi apparatus?
the GA has a receiving side for the transport vesicles. The transport membrane fuses with GA and places its contents in. GA changes ER products as it goes through the stacks. The shipping side of GA puts products in vesicles again to travel off or become part of plasma membrane/part of another organelle.
How does the GA modify ER products?
Removes/substitutes sugars from glycoproteins, adds molecular tags like phosphate groups (to help sort for different destinations).
What is the uncertainty of a low power microscope diameter?
+/- 100 micrometers
What is the uncertainty of a high power microscope diameter?
+/- 25 micrometers
