Cells and Cell Structures Flashcards
What is The Cell Theory?
The work of many scientists over many years contributed to the cell theory.
The Cell Theory states:
All living things are made of one or more cells.
The cell is the basic unit of all living things.
All cells come from pre-existing cells.
What is The Characteristics of Living Things?
Most lists include the following:
Living things are made up of one or more cells and have DNA as their hereditary material
Living things reproduce
Living things grow and develop
Living things respond to stimuli
Living things obtain and use energy
Other characteristics include:
Evolve
Maintain homeostasis
What structures contains all of the materials necessary for life?
Membrane-covered
What is the Smallest structural and functional unit of an organism that can be considered alive?
cells
Cells come in a what shapes and sizes?
variety
What do All cells have?
Have a cell membrane
Contained DNA at some point
Have sub-cellular structures (not necessarily organelles-only eukaryotes have organelles…but we’ll get to that soon!)
What are Two Kinds of Cells
prokaryotic
eukaryotic
What features do Prokaryotic Cells have that Eukaryotic cells don’t?
No membrane-bound organelles
No nucleus
What features do Eukaryotic Cells
have that Prokaryotic Cells don’t?
Have membrane-bound organelles
Have a nucleus
Compartmentalization allows for different parts of a cell to be specialized for different functions.
On average are approximately 10x larger than prokaryotic cells
Prokaryote Structure
Includes bacteria and archaea
Are unicellular
Have cell membrane
NO other membranes within the cell
Therefore, they do NOT have organelles
Have a cell wall outside of the cell membrane
Usually have a single circular, double-stranded DNA chromosome in the nucleoid region, which is not membrane-bounded
Have sub-cellular structures, predominantly ribosomes which produce proteins
They do not have organelles
What is a Plasmids?
Plasmids – Small rings of DNA outside of the chromosome
Often carry accessory genes
What is a Flagella?
Flagella – Used to move the bacteria in aqueous environments (flagellum-singular)
What is a Capsule?
Capsule – Sticky layer of sugars and proteins outside of the cell wall that protect the cell and allow it to adhere to surfaces.
Characteristics of Eukaryotes?
Include animal, plant, and fungal cells
Can be unicellular or multicellular
Have a cell membrane
May have a cell wall (plant, algae and fungal cells have cell walls)
Have multiple organelles
Organelle
Usually have multiple linear double stranded DNA chromosomes stored in a nucleus
What is a organelle?
Organelle – Any membrane enclosed structure with specialized functions in the cytoplasm of a eukaryotic cell
Prokaryotes
* Chromosome?
Usually one; double-stranded, circular, contained in the nucleoid region
Prokaryotes
* Cell Wall?
Almost always
Prokaryotes
* Organelles?
No
Prokaryotes
Size?
Small
Prokaryotes
Unicellular or multicellular?
Unicellular
Eukaryote
Chromosome?
Usually many, double-stranded, linear, contained in the nucleus
Eukaryote
Cell Wall?
Only on plant, algae, and fungi cells. No cell walls on animal cells
Eukaryote
Organelles?
Yes. Organelle compartmentalization allows for specialization of processes within a eukaryote.
Eukaryote
Size?
On average around 10x larger than prokaryotes
Eukaryote
Unicellular or multicellular?
May be unicellular or multicellular
What is Plasma Membrane?
Composed primarily of phospholipids, but also contains proteins, cholesterol and other types of molecules.
Contains receptors that allow cells to communicate with each other.
In multicellular organisms, contains proteins that allow cells to adhere to structures outside of the cell to form tissues
Is selectively permeable-allows the cell to maintain homeostasis
Is the outer barrier of a cell (a cell wall is considered to be extracellular)
What is a Nucleus?
Control center of the cell
Contains the cell’s chromosomes
Surrounded by a nuclear envelope to protect the DNA
Nuclear envelope has pores to allow for some transport of material in and out of the nucleus
What is Nucleolus?
Dense region of DNA contained within the nucleus where ribosome production begins
RNA is synthesized and combined with proteins to form ribosomes
Some cells have more than one nucleoli
What is Cytoplasm?
The liquid and all of the organelles within a cell except for the nucleus.
The liquid itself is referred to as the cytosol and contains dissolved molecules necessary for the cell to survive
What is Ribosomes?
Produce proteins for the cell
In eukaryotes, may be free floating in the cytoplasm or may be attached to the rough endoplasmic reticulum.
Free floating ribosomes produce proteins to be used within the cell
Attached ribosomes generally produced proteins that will either be embedded in the plasma membrane or will be secreted from the cell
Depending on a cell function, cells have very different amounts of ribosomes
What is Rough Endoplasmic Reticulum?
Series of flattened membrane-bound sacs that have ribosomes attached to it.
Plays a role in the production of secreted proteins by transporting those proteins as they are being produced by bound ribosomes.
Proteins produced by bound ribosomes fold within the rough endoplasmic reticulum.
Additional modifications may be made to proteins within the rough endoplasmic reticulum.
What is Smooth Endoplasmic Reticulum?
Series of flattened membrane-bound sacs that have NO ribosomes attached to it.
Plays a role in the production lipids within a cell
Depending on the cell type, may have specialized functions including sugar metabolism, calcium storage or detoxification
What is Vesicles?
Small, membrane-enclosed sacs involved in the transport of materials within a eukaryotic cell
What is Golgi Apparatus?
Complex of flattened membrane sacs that stores, modifies and ships proteins that have been produced by ribosomes bound to the rough endoplasmic reticulum
Lysosomes originate from the Golgi apparatus
What is Lysosomes?
Organelles that contain hydrolytic enzymes
Hydrolytic enzymes break down unnecessary cell molecules and organelles
Some immune system cells use lysosomes to destroy pathogens
Play a role in programmed cell death (apoptosis)
What is Cytoskeleton?
Network of fibers extending throughout the cytoplasm that organizes the structures of the cell
Supports the cell and maintains its shape
Controls the positions and movements of organelles and vesicles within the cell
Interacts with extracellular structures, anchoring the cell
What is Centrosomes?
Organize cell division in animal cells
Comprised of two centrioles
What is Eukaryotic Cell Wall?
Made of different material than a prokaryotic cell wall
For eukaryotes, seen in plant, algae and fungi cells; animal cells do not have a cell wall
Functions primarily to protect the cell
What is Mitochondria?
Found in nearly all eukaryotes
Function in cellular respiration, converting the energy that was stored in glucose into energy stored in ATP
What is Chloroplast?
Found in plant and algae cells
Function in photosynthesis, which stores energy in sunlight as chemical energy in carbohydrates.
What is the Endosymbiont Theory?
An early ancestor of eukaryotic cells engulfed an oxygen-using prokaryotic cell
The engulfed cell became an endosymbiont
Endosymbiont – a cell living within another cell
Over time, the host cell and endosymbiont merged into a single organism
What is the Evidence for Endosymbiont Theory?
Evidence:
Both mitochondria and chloroplasts have double membranes
Both mitochondria and chloroplasts have their own ribosomes and DNA in the form of circular chromosomes
Both mitochondria and chloroplasts can reproduce on their own, independently of cell division
