Cells Flashcards
Living organisms are classified into 3 domains:
Bacteria, Archaea and Eukarya
Which domain(s) are pokaryotic?
Bacteria and archaea
Which domain(s) are eukaryotic?
Eukarya
Characteristics of prokaryotes
(4)
- single celled organisms
- Lack membrane-bound organelles
- DNA is not seperated from the cytoplasm in a nucleus
What can be said about bacteria
(2)
Bacteria are the most diverse and widespread prokaryotes and are now classified into multiple kingdoms.
What can be said about archaea?
Archaea live in Earth’s extreme environments, such as salty lakes and boiling hot springs.
Characteristics of eukarotes
(3)
- contain membrane bound organells
- more complex organisms
- DNA in a nucleus - seperated from the cytoplasm by a membrane
Domains of eukarya
(4)
- Plantae
- Fungi
- Animalia
- Protista
3 major characteristics of prokaryotic cells
(3)
- Within the cytoplasm, much less and/or smaller organelles or none
- Rigid cell walls: surrounding the plasma membrane
- No membrane bound nucleus: the genetic material (DNA) is found in the nucleoid region
Cytoplasm
the region between the nucleus and the membrane bounding the cell which consists of a semifluid medium called the cytosol, in which are found various organelles.
What can be said conserning the size of eukaryotic and prokaryotic cells?
Eukaryotic cells are generally much larger than prokaryotic cells
Why are cells small
a smaller object has a greater ratio of surface area to volume
Do larger organisms have larger cells than smaller organisms? Explain
No, they do not. They simply have more cells
Example of a cell where a high ratio of surface area to volume is important
Intestinal cells
What is one way to increase surface area without a big increase in volume?
Microvilla - long projections on cells surfaces
Key roles of the cell membrane
(5)
- Controlling cell function
- cell adhesion
- recognition and communication
- keeping its molecules of life from dissipating away
- keep out foreign molecules that damage or destroy the cells components and molecules
The plasma membrane and the various internal membranes of cells consist of a _______ of ________ with _____________ attached to or imbedded in it.
The plasma membrane and the various internal membranes of cells consist of a double layer of phospholipids with proteins attached to or imbedded in it
What is found along the membrane apart from phospholipids?
Proteins
Nucleus
Contains DNA and controls cellular activity
Nucleolus
A region where components of ribosomes are synthesized and assembled
What happens after ribosomes are asesembled in the nucleolus?
They pass through the nuclear pores to the cytoplasm, where they combine to form ribosomes (the site of protein synthesis)
the DNA is organized along with proteins into a material called _______
the DNA is organized along with proteins into a material called chromatin
What happens to chromatin as a cell prepares to divide?
the stringy, entangled chromatin coils up (condenses) becoming thick enough to be discerned as separate structures called chromosomes
What is a chromosome formed from?
A chromosome is formed from a single DNA molecule that contains many genes