Cell Types/Structure Flashcards
Unit 1, Cell Biology
What are/is the organelle in prokaryotic cell?
The only organelle is ribosomes, the type is called 70s ribosomes.
Define organelles
Organelles are discrete structures in cells that are adapted to perform a specific function
What do not meet the requirements of being classified as an organelle?
Cell wall - It is located outside of the membrane, it is extracellular. It is not in the cell so not an organelle
Cytoplasm - It is composed of about 80 percent water and many dissolved solutes. It is not specialized to perform a specific function
Cytoskeleton - It is composed of many different types of filaments and tubules. Not a discrete (individual, distinct) structure, so not an organelle.
Define Nucleus
- Contains DNA, which stores information for making proteins
- Contains nucleolus, which is where ribosome subunits are made.
- Has a double membrane with pores, allows eukaryotic cells to separate the activities of gene transcription and translation.
Advantages of the seperation of the nucleus and cytoplasm?
- The seperation protects DNA
- Allows for modification of the DNA message before leaving the nucleus.
Define transcription
This is the process in the nucleus that copies DNA’s code into molecules of a type in RNA.
Define translation
The process of assembling protein at ribosomes (in the cytoplasm) using the transferred code. DNA itself never leaves the nucleus.
Benefits of the double membrane of the nucleus?
- Proteins are made in the cytoplasm at ribosomes
- Many substances like mRNA and ribosomes need to leave the nucleus
- Many of the above are large and therefore the nucleus needs fairly large holes or pores. Double membrane of the nucleus is used to make these pores.
- Reassembly of the membrane is easier if it is a double layer, after cell division.
Define ribosomes
They catalyze/produce proteins.
They are composed of two subunits that come together to for a functioning structure.
Define rER
80s ribosomes are attached to the outside.
The bound ribosomes make proteins and release them to the inside of the cisternae.
Proteins are carried through cisternae and then into vesicles which move on to the golgi apparatus.
Define vesicles
Tiny sacs (single membrane layer) used to transport material/liquids
What does rER look like?
Consists of flattened membrane saves (cisternae) continuous with the nuclear membrane.
Define sER
They have no ribosomes
Produces lipids
Extends throughout the cell
What does sER look like?
Series of connected flattened membrane sacs
What does Golgi apparatus look like?
Like rER it contains flattened membrane sacs called cisternae.
They are shorter and curved with no ribosomes and many vesicles nearby
Define Golgi apparatus
Stores, processes and modified the proteins. Proteins are made by vesicles from the rER.
After modification, the proteins are passed through vesicle then to the plasma membrane for secretion or repair of the cell membrane or to lysosomes.
Define transport vesicle
Move substances within the cell, bud off one spot, fuse with another
Define secretory vesicles
secrete substances out of the cell and create new cell membrane.
What does lysosomes look like?
Small, spherical, single membranes.
Define lysosomes
Formed from golgi vesicles
Obtains digestive enzymes to break down worn out organelles, or even whole cells
What does mitochondria look like?
They are double membranes, smooth outer membrane with inner membrane folding inwards.
Usually oval, spherical but can vary.
Define mitochondria
They produce ATP (energy molecule) by aero is cell respiration, “power house of the cell” large surface for cellular metabolism.
They contain their own DNA, can reproduce independently, produces and contains its own 70s type rivosimes
What does chloroplasts look like?
Double membranes, flattened sacs called thylakoids appear in stacks.
Usually spherical/oval but can vary
Define chloroplasts
They produce glucose/organic compounds by capturing light energy. Insides contain chlorophyll
Only in plant cells
