Cell Structure Flashcards
Nucleus
contains DNA which controls the activities of the cell by containing the base sequences (the ‘instructions’ needed to make proteins. The DNA is associated with histone proteins and referred to as chromatin which is wound into structures called chromosomes.
Nucleolus
this is a region within the nucleus where ribosomes are made
Nuclear envelope
double membrane which surrounds the nucleus. It contains pores which allows small molecules to pass into the cytoplasm but keeps chromosomes and other contents safely inside its walls.
Rough endoplasmic reticulum (RER)
the RER is an extension of the nuclear envelope and is coated with ribosomes. It facilitates protein synthesis by providing a large surface area for ribosomes. It then transports the newly synthesised proteins to the Golgi apparatus
Smooth endoplasmic reticulum (SER)
synthesises lipids including cholesterol and steroid hormones
Golgi apparatus
made up of a group of fluid-filled membrane-bound flattened sacs surrounded by vesicles.
It receives proteins from the RER and lipids from the SER.
It modifies the proteins and lipids and repackages them into vesicles.
Ribosomes
ribosomes are responsible for the translation of RNA into protein (protein synthesis)
Mitochondria
site of ATP production during aerobic respiration. It contains a double membrane with folds called cristae, which provides a large surface area for respiration.
Lysosomes
phospholipid rings which contain digestive enzymes separate from the rest of the cytoplasm.
Lysosomes engulf and destroy old organelles or foreign material.
Cell surface membrane
consists of a phospholipid bilayer with additional proteins to serve as carriers. It also contains cholesterol. The plasma membrane contains the cell contents and holds the cell together, whilst controlling the movement of substances into and out of the cell.
What is the purpose of cholesterol in the cell surface membrane
To regulate membrane fluidity
Centrioles
these are bundles of microtubules which form spindle fibres during mitosis .
They are also important for the formation of cilia and flagella.
They are only found in animal cells.
Cell wall
In plants: rigid structure made of cellulose
In fungi: chitin
In prokaryotes: murein
It provides support to the cell and is not found in animal cells
Chloroplasts function
the site of photosynthesis
Chloroplasts structure
It is enclosed by a double membrane and has internal thylakoid membranes arranged in stacks to form grana linked by lamellae.
These structures are found only in plants and certain types of photosynthesising bacteria or protoctists.
Flagella
Structure:a tail-like structure which are made up of bundles of microtubules.
Functions:The microtubules contract to make the flagellum move and propel the cell forward.
Cells with a flagellum include sperm cells, which use it to swim up the fallopian tubes to fertilise the egg cell.
Cilia
finger-like projections found on the surface of some cells. These also contain bundles of microtubules which contract to make the cilia move.
Cilia are found on epithelial cells lining the trachea and move to sweep mucus up the windpipe.
Vacuole
stores cell sap and may also store nutrients and proteins
It helps to keep plant cells turgid.
Which organelle are involved in proteins production
Nucleus , nuclear envelope, ribosome,RER, Golgi apparatus, cell surface membrane
Vesicles-transport and secretory
What is the first stage of protein synthesis
The gene that has the coded instructions for a protein such as insulin, housed on chromatin in the nucleus, is transcribed into a length of RNA, called messenger RNA (mRNA).
What is the second step in proteins synthesis
The mRNA are pass through the nuclear envelope pores and goes to the ribosome
What is the third step in proteins synthesis
The ribosome translate the instructions from the mRNA to make the proteins
E.G insulin
What is the fourth step of protein synthesis
The proteins pass through the cisternae of the RER and is folded then is packaged into transport vesicle and goes to the Golgi apparatus
Via microtubules and motor proteins
What is the fifth step of protein synthesis
The vesicles fuses with the Golgi apparatus where proteins are chemical modified
The proteins is then packaged into transport into secretory vesicle and the is fuse with the cell surface membrane where it is released
The process is called exocytosis
