Chapter 4 - Cell structure Flashcards
Hierarchy from cells to organism
Cells to tissues to organs to organ systems to organisms
Prokaryotic cell size range
.1 - 5 micrometers
Eukaryotic cell size range
10 - 100 micrometers
In order to look at cells in a microscope what must happen?
They must be stained since they are transparent, the staining process kills them
Oil immersion allows lenses to magnify to what power?
1000x
How are electron microscopes different than regular microscopes?
They use a beam of electrons rather than light, this allows for higher magnification providing great detail. This is because electrons have a very short wavelength while photons are much longer.
What is the difference between a scanning electron microscope and a transmission electron microscope?
Scanning electron microscope visualizes surface characteristics, while a transmission electron microscope penetrates the cell surface to study internal structure
Who coined the term cell for box like structures they observed in cork?
Robert Hooke
Who observed bacteria and protozoa(paramecium) in the 1670s
Anton Van Leeuwenhoek
Plants have cell walls while animals have…
Cell membranes
Who proposed the unified cell theory in the 1830s?
Matthias schleiden, and Theodor Schwann
What are the 3 things listed by the unified cell theory?
1) all living things are composed of one or more cells
2) the cell is the basic unit of life
3) new cells arise from prexisting cells
Prokaryotic cells are mostly what?
Bacteria
What are the 4 common features of all cells? (eukaryotic and prokaryotic)
1) plasma membrane (protective covering that separates the cells external from internal environment)
2) cytoplasm (includes a cells interior components suspended in a jelly like substance called Cytosol)
3) DNA (genetic material which dictates inheritance and controls metabolism)
4) ribosomes (synthesize proteins)
Are viruses or prions considered living? If so which ones, or are both?
None of them are
Most distinctly what do prokaryotic cells lack that eukaryotic cells have?
First they are unicellular instead of multicellular, they lack a membrane bound nucleus and membrane bound organelle’s
Where is prokaryotic DNA found in a cell?
The nucleoid region
What type of cell walls can bacteria have?
They have a peptidoglycan cell wall that is either gram positive or gram negative
It is a protective layer that helps maintain a specific shape, and prevents them from dehydration
How can you tell if a bacteria is gram positive or gram negative?
By a process called a gram staining process, if it is blue it is positive, if red it is negative
Many bacteria have capsules which allows them to attach to surfaces, what is the capsule made out of?
Polysaccharides
Some bacteria’s have a structure to help them move (locomotion). What is the structure called?
Flagellum
what does a pili allow to happen in bacteria?
Exchange of DNA in a process called bacterial transformation
What does fimbriae allow bacteria to do?
Attach to other cells
The small cell size of prokaryotic cells allows for what in terms of getting things in and out of the cell?
It allows ions, organic molecules, and waste products to diffuse quickly though the cells interior
Different from eukaryotic cells which have a much more sophisticated way of transportation
Why is it an advantage size wise for cells to be small? In terms of volume and radius?
Smaller spheres have a much larger surface area to volume than large spheres
Multiple foldings of a plasma membrane allows what?
An increase in surface area
This is how a lot of eukaryotic cells have adapted allowing them to become larger
Form follows
Function
What does organelle literally mean?
Little organ
What are the 2 forms DNA takes?
Chromatin is the unwound form, and chromosomes are the condensed form
What does the plasma membrane seperate?
The internal from the external environment of the cell
You can identify the cell on the plasma membrane by what molecules?
The glycoproteins
What type of bilayer does the plasma membrane have, and what is embedded in them?
It has a phospholipid bilayer with proteins embedded in them
How does water get into a plasma membrane?
Through small channels call aquaporins
What can and can’t go straight through a plasma membrane? Ions, oxygen, carbon dioxide, organic molecules, ammonia
Ions, oxygen, and carbon dioxide can go right through. Organic molecules and ammonia can’t go straight through.
Plasma membranes may fold into microvili like in the small intestine, what does this increase?
Surface area!
What is the region between the plasma membrane and the nucleus?
The cytoplasm
What gel like material does the cytoplasm contain?
Cytosol
Other than Cytosol what else does the cytoplasm contain?
A cytoskeleton and organelles suspended in the Cytosol, and many dissolved molecules and ions including many types of proteins
How much of the cytoplasm is water?
70-80%
What is the most prominent organelle in a eukaryotic cell?
The nucleus
What does the nucleus house?
DNA, which is responsible for reproduction and directing the cells production of proteins and ribosomes
What is the membrane for the nucleus called?
The nuclear envelope
What area of the nuclear envelope controls the passage of ions, and other molecules?
The pores
What is the nucleoplasm?
A semi solid fluid inside the nucleus that contains the chromatin (DNA) and the nucleolus
What holds the strands of DNA together?
Histone proteins
What are the differences in chromosomes from eukaryotic and prokaryotic organisms?
Prokaryotes have a single circular chromosome, while eukaryotes have two or more linear chromosomes
What are non reproductive cells called?
Somatic cells
When are chromosomes visible?
When the cell is dividing
When cells are in their growth and maintenance stage the chromosomes are what?
They are unwound
What are unwound chromosomes complexes called?
Chromatin
Why are chromosomes unwound into chromatin?
To make it easy to access the genes
What are condensed chromatin called?
Chromosomes
What are the dark areas within the nucleus?
The nucleolus
What are the main things that the nucleolus contains?
Ribosmal RNA, with associated proteins
rRNA and associated proteins make what once outside of the nucleus?
Ribosmal subunits
Ribosmal subunits assemble once outside where?
The nucleus
Where are proteins made?
In ribosomes
Where are ribosomes found? (A few places)
They can float freely in the cytoplasm, may be attached to the plasma membranes inner surface, or attached to the endoplasmic reticulum (RER)
What organelle are large proteins and RNA complexes?
Ribosomes
Ribosomes consist of what subunits?
Two sub units small and large)
What, how, and where do ribosomes receive instruction?
They receive instructions for protein synthesis from the nucleus in the form of the nucleotide sequence carried by messenger RNA (mRNA)
How does DNA get the sequence to mRNA?
The DNA in the nucleus transcribes the nucleotide sequence of the gene into the nucleotide sequence of the mRNA