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40 Cards in this Set
- Front
- Back
What is the ultrastructure of a cell? |
Each cell has an internal structure that suits its function |
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What type of cell is an epithelial cell? |
A eukaryotic cell |
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What are the characteristics of eukaryotic cells? |
Have a distinct nucleus Possess membrane-bounded organelles |
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Name an example of a prokaryotic cell |
Bacteria |
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What type of microscope is used to see the organelles in a cell? |
Electron microscope |
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What is inside the nucleus? |
Contains organism's hereditary material (DNA) and controls cell's activity |
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What is the nuclear envelope? |
A double membrane that surrounds the nucleus Its outer membrane is continuous with the endoplasmic reticulum of the cell and often has ribosomes on its surface |
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What is the function of the nuclear envelope? |
Controls the entry and exit of materials in and out of the nucleus Contains reactions taking place within it |
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What is the function of the nuclear pores? |
Allow passage of large molecules, such as messenger RNA, out of the nucleus |
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What is the nucleoplasm? |
The granular, jelly-like material that makes up the bulk of the nucleus |
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What is chromatin? |
The DNA found within the nucleoplasm This is what chromosomes are when the cell is not dividing |
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What is the nucleolus? |
Small spherical body within the nucleoplasm |
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What is the function of the nucleolus? |
Manufactures ribosomal RNA and assembles ribosomes |
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What are the 3 functions of the nucleus? |
1. Act as a control centre of the cell through the production of mRNA and hence protein synthesis 2. Retain genetic material of the cell in the form of DNA or chromosomes 3. Manufacture ribosomal RNA and ribosomes |
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What is a mitochondrion made up of? |
Double membrane Cristae The matrix |
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What is the function of the double membrane? |
The outer one controls the entry and exit of material The inner membrane is folded to form extensions known as the cristae |
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What is the function of the cristae? |
Shelf-like extensions which provide a large surface area for the attachment of enzymes involved in respiration |
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What does the matrix contain? |
Protein Lipids Traces of DNA |
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What does the matrix do with its contents? |
Allows mitochondria to control the production of their own proteins |
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What is the endoplasmic reticulum? |
An elaborate, three-dimensional system of sheet-like membranes, spreading through the cytoplasm of the cells Continuous with the outer nuclear membrane Membranes enclose flattened sacs called the cisternae |
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What are the two types of endoplasmic reticulum? |
Rough endoplasmic reticulum Smooth endoplasmic reticulum |
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What is present on the outer surface of the RER? |
Ribosomes |
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What are the functions of the RER? |
1. Provide large surface area for the synthesis of proteins and glycoproteins 2. Provide pathway for the transport of materials throughout the cell, especially protein transport |
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What is the physical appearance of the SER? |
Lacks ribosomes on its surface More tubular appearance |
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What is the function of the SER? |
Synthesis, store and transport lipids and carbohydrates |
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What does the Golgi apparatus consist of? |
Stack of membranes that make up flattened sacs with small rounded hollow structures called vesicles |
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What is the correct term for flattened sacs? |
Cisternae |
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What is the process of the Golgi apparatus? |
-Modifies proteins from RER by adding non-protein components e.g carbohydrate -Also labels proteins, allowing them to be sorted and sent to correct destinations -Once sorted, modified proteins and lipids are transported in vesicles which are regularly pinched off from the ends of Golgi cisternae -Vesicles move to cell surface, where they fuse with membrane and release contents to outside |
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What are the functions of the Golgi apparatus? |
-Add carbohydrate to protein to form glycoproteins -Produce secretory enzymes e.g those secreted by pancreas -Secrete carbohydrate e.g those used to make cell walls in plants -Transport, modify and store lipids -Form lysosomes |
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When are lysosomes formed? |
When vesicles produced by Golgi apparatus contain enzymes |
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What do lysosomes isolate? |
Isolate potentially harmful enzymes from rest of cell before releasing them |
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Where do lysosomes release enzymes into? |
Outside the cell Into a phagocytic vesicle within the cell |
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What are the functions of lysosomes? |
-Break down material ingested by phagocytic cells e.g white blood cells -Release enzymes to the outside of cell (exocytosis) in order to destroy material around cell -Digest worn out organelles so that useful chemicals which they are made from can we re-used - Completely break down cells after they have died (autolysis) |
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What are ribosomes? |
Small cytoplasmic granules found in cells |
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Where are ribosomes found? |
Cytoplasm RER |
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What are the two types of ribosomes? |
80S type 70S type |
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Where are the two types of ribosomes found? |
80S type- Eukaryotic cells 70S type- Prokaryotic cells |
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What is in the both subunits of a ribosome? |
Ribosomal RNA Protein |
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What is RNA? |
Ribonucleic acid Its principal role is to act as a messenger carrying instructions from DNA for controlling the synthesis of proteins |
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What are microvilli? |
Finger-like projections of an epithelial cell Increases surface area to allow more efficient absorption |