2.1 Eukaryotic cells Flashcards
Where are eukaryotic cells found?
In animal and plant cells
Where are prokaryotic cells found?
In single celled organisms, such as bacteria
What is the function of the nucleus?
It contains the DNA and instructs the rest of the cell (organelles)
What is ultra structure?
It is the internal structure of a cell, can be seen under an electron microscope
What do all organelles in a eukaryotic cell have and why?
A membrane which protects the organelle and controls the conditions within it (input and output)
What does the nucleus contain?
- nuclear envelope
- nuclear pores
- chromatin
- nucleolus
What is the nuclear envelope?
A double membrane controlling material entry and exit
What are nuclear pores?
Gaps in the membrane allowing large molecules such as mRNA out of the nucleus
What is chromatin?
Made out of proteins and DNA, it controls cell activity
What does the nucleolus do?
It is responsible for making ribosomes
What are the functions of the nucleus?
- produce mRNA for protein synthesis
- retain genetic material in the form of DNA or chromosomes
- manufacture ribosomal RNA and ribosomes
What does the mitochondria contain? And what is the mitochondria?
• a double membrane
• Cristoe
• matrix
- the site of aerobic respiration, energy is derived from fuels here and converted into ATP
What does the double membrane do?
The outer membrane controls the flow if materials in/out
What is Cristoe and what does it do?
• it is the extension of the inner membrane it increases surface area for the attachment of enzymes
What is the matrix and what does it do?
It is a semi rigid structure containing proteins, lipids, trace DNA, and the enzymes involved in respiration
it is also the site of the krebs cycle
What is the endoplasmic reticulum?
A system of sheet like membranes throughout the cytoplasm
What are the two types of endoplasmic reticulum?
there is the ROUGH ENDOPLASMIC RETICULUM and the SMOOTH ENDOPLASMIC RETICULUM
What does the rough endoplasmic reticulum look like, and why?
It is bumpy because it has ribosomes embedded on its surface to give it a large surface area for protein synthesis
What is the function of the rough endoplasmic reticulum?
It acts as a pathway to transport proteins out of the cell
What does the smooth endoplasmic reticulum look like and why?
It is smooth as it has no ribosomes embedded on the surface
What is the function of the smooth endoplasmic reticulum?
Used for protein synthesis, it stores and transports lipids and carbohydrates
Where is the reticulum found?
In close proximity of not attached to the nucleus
What does the Golgi apparatus do?
It modifies, packages and transports lipids and proteins
What is the structure of the Golgi apparatus?
- similar to the smooth ER
- more compact
- flattened stacks of membranes with rounded structures called vessicles
What are the functions of the Golgi apparatus?
- adds carbohydrates to proteins to make glycoproteins
- produces secretary enzymes
- secretes carbohydrates
- transports and modifies lipids
- forms lysosomes
What are lysosomes?
- formed from the Golgi apparatus they contain digestive enzymes
- round organelle surrounded by a membrane with no clear internal structure
What do lysosomes do?
- isolate potentially harmful enzymes from the rest of the cell
- break down material ingested by phagocytic cells such as white blood cells
- release enzymes to the outside of the cell
- digest worn out organelles
- break down cells when they have died
Where a ribosomes found?
In the cytoplasm floating freely or attached to the rough ER
What are ribosomes used for?
Protein synthesis
What are the two types of ribosomes?
- 80s
* 70s
Where are 80s found?
In eukaryotic cells, they are about 25nm
Where are 70s found?
Found in prokaryotic cells, they are smaller
What are microvilli?
Finger like projections of epithelial cells to increase surface area for absorption
What make up the cytoskeleton?
Micro tubules
Micro filaments
What are microfilments are what are they involved in?
- protein action
* Involved in cell movement and cell division
What are micro tubules and what are they involved in?
- globular proteins that form tubes
- determine cell shape
- direct movement of organelles within the cell
What does the nucleus make?
MRNA for protein synthesis
Manufactures ribosomal RNA and ribosomes
What are ribosomes made up of?
Proteins and RNA
What is the plasma cell surface membrane?
A lipid bilayer in which proteins are embedded
Where is the cell surface membrane found?
On the surface of animal cells
Just inside the cell wall of plant cells and prokaryotic cells
What does the cell membrane do?
Regulates movement of substances in and out of the cell
What molecules does the cell surface membrane have?
Receptor molecules allowing it to respond to chemicals like hormones
What is the cell wall?
A rigid structure found in plant cells that consists mainly of the carbohydrate cellulose
What is the function of the cell wall?
To support the plant cells (leaves, roots and stems)
What are vesicles?
Small fluid filled sacs in he cytoplasm that are surrounded by a membrane
What do vesicles do?
They transport substances in and out of the cell (via the cell membrane) and between organelles
Where are vesicles formed?
Some are formed at the Golgi apparatus or the ER
Others form at the cell surface
What is centriole?
Small hollow cylinders made of microtubules
Where are centrioles found?
In animal cells
Only in some plant cells
What are centrioles involved in?
The separation of chromosomes in cell division
What is cilia?
Small hair like structures found on the surface membrane of some animal cells
What does cilia look like in cross section?
- Has an outer membrane
* Nine pairs of protein molecules on the outside and two micro tubules in the middle
What do the micro tubules in the cilia allow?
The cilia to move
What is the movement in cilia used for?
It is used by the cell to move substances along the cell surface
What are flagella?
- like cilia but longer
* they stick our from the cell surface
What does flagellum look like?
- surrounded by a plasma membrane
* inside they have a pair of micro tubules in the centre and 9 pairs around the edge
What makes flagellum move?
The micro tubules contract to make flagellum move
What is flagella used for?
It is used to make cells move, it acts like an outward motor
E.g. When a sperm cell swims
What are chloroplasts?
Small flattened structures found in plant cells.
What does a chloroplast do?
- It is the site of photosynthesis
* Some parts of photosynthesis happen in the grana and others in the strong
What is the structure of chloroplasts?
- surrounded by a double membrane
- has membranes inside called thylakoid membranes
- these membranes are stacked to form grana
- grana are linked by lamella (thin prices of thylakoid membrane)
How big are eukaryotic cells?
10-100 micrometers
