AQA Biology 3.3 Structure of an epithelial cell

Charlotte Hewson
Flashcards by Charlotte Hewson, updated more than 1 year ago
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AS - Level AS Biology (unit 1 - 03. cells and the movement in and out of them) Flashcards on AQA Biology 3.3 Structure of an epithelial cell, created by Charlotte Hewson on 04/29/2015.

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Question Answer
what is a eukaryotic cell? a cell with a distinct nucleus and posses membrane bound organelles
what does a nucleus do? contains cells hereditary material and controls cells activities
how big is the nucleus? between 10 and 20 um
what 5 parts is the nucleus made up of? -nuclear envelope -nuclear pores -nucleoplasm -chromatin -nucleolus
what is the nuclear envelope? double membrane that surrounds the nucleus
what is the nuclear envelope connected to? ER
what does it do? controls entry and exit of materials and contains reactions occurring within the nucleus
what do nuclear pores do? allow passage of large molecules out of the nucleus such as mRNA
what is nucleoplasm? granular, jelly-like material that makes up the bulk of the nucleous
what is chromatin? the DNA found within the nucleoplasm. diffused form that chromosomes take when cell isn't dividing
what is a nucleolus? a small spherical body within the nucleoplasm
what does the nucleolus do? makes ribosomal RNA and assembles the ribosomes
what are the three functions of the nucleus? -act as control centre of cell through production of mRNA and hence protein synthesis -retain genetic material in form of DNA or chromosomes -make ribosomal RNA and ribosomes
what shape are mitochondria? rod shaped
how big are mitochondria? 1-10 um in length
what are the three parts of a mitochondrion? double membrane, cristae and matrix
what does the double membrane do? surrounds organelle. outer one controls entry and exit of material. inner is folded into cristae
what are cristae? shelf like extensions of the inner membrane.
what do they do? provide large surface area for attachment of enzymes involved in respiration
what is the matrix? semi-rigid material that makes up remainder of mitochondrion
what does the matrix contain? protein, lipids and traces of DNA
what does this allow the mitochondrion to do? control the production of their own proteins
what enzymes are found in the matrix? those for respiration
what are mitochondria responsible for making? ATP
where are high numbers of mitochondria found? Muscle and epithelial cells
what is ER? endoplasmic reticulum. 3D system of sheet-like membranes in cytoplasm. attached to the nuclear membrane
what does ER contain? flattened sacs called cisterane
what are the two types? RER and SER
What is the characteristic of RER? has ribosome's on the outer surface of membranes
what is the function of RER? -provide large SA for synthesis of proteins and glycoproteins -provide a pathway for the transport of materials, especially proteins, throughout the cell
what is the characteristic of SER? lacks ribosomes on its surface and is often more tubular in appearance
what are the functions of SER? -synthesise, store and transport lipids
what function would men a cell needs lots of ER? manufacture and store large quantities of carbs, proteins and lipids
what are examples of a cells that do this? liver and secretory cells e.g. epithelial cells that line the intestines
what kind of cells have Golgi apparatus, eukaryotes or prokaryotes? almost all eukaryotes
describe the structure of golgi apparatus a stack of membranes that make up flattened sacs called cisternae
what are the 5 functions of the golgi apparatus? -add carbs to proteins to form glycoproteins -produce secretory enzymes e.g. in pancreas -secrete carbs e.g. to make cell walls in plants -transport, modify & store lipids -form lysosomes
were are golgi apparatus well developed? in secretory cells like epithelial cells lining the intestines
when are lysosomes formed? when the vesicles produced by golgi apparatus contain enzymes such as proteases and lipases
how many enzymes can be contained in one lysosome? up to about 50
what is the purpose of lysosomes doing this? they isolate potentially harmful enzymes from the rest of the cell before releasing them outside the cell or into a phagocytic vessel within the cell
what are the 4 functions of lysosomes? -break down materials ingested by phagocytic cells, such as white blood cells -release enzymes to the outside of the cell (exocytosis) in order to destroy material around the cell -digest worn out organelles to re-use useful chemicals -completely break down dead cells (autolysis)
where are lysosomes most abundant? secretory cells such as epithelial cells and phagocytic cells
what are the two types of ribosome? -70S type -80S type
where are 70S type found? Prokaryotic cells
where are 80S type found? eukaryotic cells
how many subunits does a ribosome have? 2
what makes these subunits different? their size
what does each subunit contain? ribosomal RNA and proteins
what are microvilli? tiny projections of the epithelial cell
what are they for? increase SA for efficient absorption
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