Cells Flashcards
What are centrioles? What type of cells have them? What are they involved in? Make sure you know what they look like?
- every animal cell has one pair of centrioles (they are not found in plants and fungi)
- they are hollow cylinders made up of a ring of nine protein microtubules (polymers of globular proteins arranged in a helix to form a hollow tube)
- They are involved in the formation of the spindle during nuclear division and in transport within the cell cytoplasm
What are centrioles formed from? What are they involved in and what do they produce?
- centrioles are formed from microtubules and are involved in cell division - producing spindle fibres
What are eukaryotic cells? Give examples
- eukaryotic cells are cells that contain a nucleus and other membrane-bound organelles
- eukaryotic cells are animal cells, plants, fungi
What is the Golgi apparatus? What does it do?
- stacks of flattened, membrane-bound sacs formed by fusion of vesicles from the ER
- it modifies proteins and lipids before packaging them into Golgi vesicles (the vesicles then transport the proteins and lipids to their required destination)
What are vesicles? What does the smooth ER form? Where do the vesicles (from the ER) enter the Golgi apparatus and where do they leave the Golgi apparatus?
- vesicles are compartments formed by a lipid bilayer separating its contents from the cytoplasm
- the vesicles (from ER) enters the Golgi apparatus by fusing with the cis face and move towards the trans face (where they leave)
What are lysosomes? What are they involved in? What are the used by? What is an example of a lysosome?
- they are specialist forms of vesicles (spherical sacs) which contain hydrolytic (hydrolysis) enzymes and they are bound by a single membrane
- involved in the breakdown of unwanted structures within the cell e.g. worn-out organelles
- they are used by cells of the immune system and in apoptosis (programmed cell death)
- the acrosome is a specialised lysosome
What is mitochondria (singular mitochondrion) the site of? What is it surrounded by? What does it contain? What else is found in the matrix and why are they needed?
- it is the site of aerobic respiration (within eukaryotic cells)
- it is surrounded by a double membrane with the inner membranes folded to form finger-like projections called cristae
- the matrix of mitochondria contains enzymes needed for aerobic respiration, producing ATP
-small circular pieces of DNA (aka mitochondrial DNA) and ribosomes are also found in the matrix, they’re needed for replication of mitochondria before cell division
Define the process of respiration?
The chemical process by which energy is released from glucose to produce ATP inside living cells
- aerobic respiration requires oxygen, anaerobic does not
What is the nucleolus?
- a dense body within the nucleus where ribosomes are made
What are prokaryotic cells? Give examples
- prokaryotic cells are cells that do not have a true nucleus or membrane-bound organelles
- prokaryotic cells are much smaller than eukaryotic cells
- examples = bacteria, archaea, mycoplasma (bacteria without cell walls)
Where are ribosomes formed? What are they composed of? Where can they be found? What are they not surrounded by? What are they the site of?
- ribosomes are formed in the nucleolus and are composed of equal amounts of RNA and protein
- these small organelles are found free in the cytoplasm or attached to the rough endoplasmic reticulum
- they are not surrounded by a membrane
- they are the site of translation, the latter part of protein synthesis
What are 80s ribosomes composed of and where are they found? What are 70s ribosomes composed of and where are they found?
- 80s ribosomes are found in eukaryotic cells
- 80S ribosomes are composed of a small 40S subunit and large 60S subunit
- 70S ribosomes are composed of a small 30S subunit and large 50S subunit
- 70s ribosomes are found in prokaryotes, mitochondria and chloroplasts
- the S stands for svedbergs, the unit used to measure how fast molecules move in a centrifuge
Where is the nucleus present? What is it surrounded by? What does it contain? What are chromosomes made of?
- nucleus is present in all eukaryotic cells
- it is surrounded by a double membrane called the nuclear envelope which has many pores
- the nucleus contains a nucleolus and contains chromatin, the material from which chromosomes are made
- chromosomes are made of sections of linear DNA tightly wound around proteins called histones
What is the smooth endoplasmic reticulum (SER)? Where is it formed? What is it involved in?
- SER is formed from folds of membrane but its function is distinct from the RER, being involved in the production, processing and storage of lipids, carbohydrates and steroids
- SER does not have ribosomes on its surface
What is the rough endoplasmic reticulum (RER) formed from? What is it covered in? What is the role of it?
- RER is formed from folds of membrane continuous with the nuclear envelope
- the surface of RER is covered in ribosomes
- the role of RER is to process proteins made on the ribosomes
What are the organelles that are involved in protein synthesis?
- the organelles that are involved in protein synthesis:
- nucleus (transcription of the DNA code occurs here)
- ribosomes (produce proteins in the process of translation)
- rough endoplasmic reticulum (RER)
- Golgi apparatus
- cell surface membrane (proteins formed within the cell are secreted here)