Ch. 4 - Cell Structure Flashcards
What three things do all cells have?
1) Plasma membrane
2) Nucleiod or nucleus
3) Cytoplasm
What is a plasma membrane?
A lipid bilayer that surrounds a cell.
What does a nucleus contain?
Contains genetic material (DNA)
What is cytoplasm?
Semi-fluid matrix that fills the interior of the cell.
What are located inside Eukaryotic cells?
Organells
What are organelles?
Specialized membrane bound compartments.
How big are typical cells?
Most are microscopic.
Who first described cells, and when?
Robert Hooke in 1665.
Who was the first to describe living cells?
What was he the first too discover?
Atoine Van Leeuwenhock.
Bacteria, several protists, nematodes (round worms), rotifers, blood cells and sperm cells.
Who studied plant tissue and developed the first modern cell theory? When?
Who made similar studies using animal cells? When?
Matthias Schleiden; 1838.
Theodore Schwann; 1839.
What are the three principles of the modern cell theory?
1) All organisms are composed of one or more cells, and metabolism and hereditary occur within these cells.
2) Cells are the smallest living things, they are the basic units of organization of all organisms.
3) Cells arise only by the division of previously existing cells
Why are cells microscopic?
1) Communication; cells need to communicate with each other to function properly. This is easier if the cells are smaller.
2) Cells synthesize units which travels by diffusion. This is much fast over short distances.
What are most bacteria protected by in their cell wall?
What are they?
Peptidoglycans.
Cross-linked complexes of carbohydrates and proteins.
What are the three internal structures of a bacteria?
1) Nucleoid (Contains DNA, but isn’t surrounded by a membrane.
2) Ribosomes
3) Cytoplasm
What do some bacteria have that is used for motion?
Flagellum.
If a cell is photosynthetic, what does it contain?
Chlorophyll.
If a bacteria is photosynthetic, where is the chlorophyll located?
On the inner side of the plasma membrane.
How far can bacteria move per second?
20 cell diameters.
What 16 organelles are found in eukaryotic cells?
1) Nucleus
2) Nuclear envelope
3) Nucleolus
4) Plasma Membrane
5) Cytoplasm
6) Mitochondrion
7) Ribosome
8) Endoplasmic Reticulum
- Rough
- Smooth
9) Golgi apparatus
10) Lysosomes
11) Vacuoles
12) Centrioles
13) Cytoskeleton
14) Chloroplasts
15) Cell walls
16) Plasmodesmata
What does the nuclear envelope surround?
Surrounds the nucleus.
What is a nucleolus?
dark spots in the nucleus; area of intense ribosomal RNA (rRNA) synthesis.
What does the plasma membrane surround?
Surrounds the cell.
What is cytoplasm?
Semi fluid matrix that fills the cell.
What does the mitochondrion provide to the cell?
Provides energy.
What are ribosomes responsible for synthesizing?
Site of protein synthesis.
What is the difference between rough and smooth endoplasmic reticulum?
- Rough: studded with ribosomes
- Smooth: no ribosomes
What is the function of the Golgi apparatus?
Used to package and deliver molecules within and beyond the cell.
What are lysosomes?
Digestive vesicles.
What is the function of vacuoles?
Used for storage.
Huge in plant cells.
What are centrioles used for?
Used in cell division.
What is a cytoskeleton?
A network of tubes and fibers that supports the cell and anchors the organelles; a scaffolding for the cell.
What do chloroplasts contain, and what process is it involved in?
Where are they found?
Chlorophyll; photosynthesis.
Found in plant cells.
What are cell walls?
In what kind of cell are cell walls located?
What are they comprised of?
Thick impermeable walls.
Found in plant cells.
Made of cellulose.
What are plasmodesmata?
In what kind of cell can they be located?
What is the function?
Holes in cell walls.
In plant cells.
Allow plant cells to communicate with each other.
What is the nuclear envelope that surrounds the nucleus made of?
Two lipid bilayers.
What are nuclear pores?
Areas of the nuclear envelope that fuse to create small holes.
What lines the nuclear pores, and what do they act as?
Lined with proteins that act as molecular channels.
What two kinds of molecules can pass through the nuclear pores?
1) Proteins moving into the nucleus to be incorporated with nuclear structures.
2) RNA and RNA/protein complexes that are being exported to the cytoplasm.
What are chromosomes?
DNA found in linear structures
How is chromatin formed?
What does this allow for?
When chromosomes are extended into very thin threads, and the DNA is fully extended.
This allows access to all of the DNA material.
When a cell is going to divide, what happens to the DNA?
How is this accomplished?
It is packaged into H shaped structures.
Using specialized packaging proteins called histones.
What are nucleosomes?
DNA that is wrapped around histones.