Flashcards in Cell Structure and Organisation Deck (67):
How is the nucleus structured?
Surrounded by double membrane (nuclear envelope).
Has nuclear pores to allow movement of mRNA and nucleotides out.
Nucleolus- rRNA is produced.
What can be found in the nucleoplasm ?
Chromatin- loosely coiled chromosomes of DNA + histone protein.
What is formed by the outer nuclear membrane?
What is the function of mitochondria (s. Mitochondrion)?
Aerobic respiration occurs to produce ATP.
Where are many mitochondria found?
Muscle tissue for contraction and liver tissue which is metabolically active
Structure of a mitochondrion-
Cristae- double membrane sac with highly folded inner membrane, increasing surface are.
Matrix-liquid containing enzymes for aerobic respiration
Circular DNA- self replicating
What are the two forms of endoplasmic reticulum and what are their functions?
Smooth- synthesises lipids
Rough- ribosomes are attached that synthesise proteins
What is the structure of ER?
Consists of flattened sacs called cisternae which extend into cytoplasm and can link with the golgi body
What is the function of the nucleus?
It contains the cell's DNA which provides the code for protein synthesis. mRNA leaves via the nuclear pores carrying the code.
How are ribosomes structured?
Very small not membrane-bound
Composed of 2 sub-units, large and small.
Come together around mRNA strand which fits into a groove
What are ribosomes made of?
Protein and rRNA
Where can ribosomes be found?
On RER or free in cytoplasm (called polysomes)
What is ribosomes' function?
What is the golgi body (apparatus)?
A crescent shaped stack of flattened membrane-bound sacs called cisternae.
What are the functions of the golgi body?
Chemically modifies proteins to form glycoproteins.
Stores and transports glycoproteins and lipids
What is the first part of the golgi body process for glycoproteins?
Vesticles containing proteins formed by RER fuse at one end of golgi sacs (forming face)
What are the second and third parts of the golgi body process for glycoproteins?
2. The protein is modified inside the cisternae.
3. Modified protein is budded off in a vesticle at other end of cisternae (maturing face)
What is the final part of the golgi body process for glycoproteins?
The vesticle containing modified protein travels to cell's outer plasma membrane where the protein is released via exocytosis
What is the structure of plasma membrane?
Formed of a phospholipid bilayer with intrinsic and extrinsic proteins and other molecules embedded into it
What are the 3 properties/functions of plasma membranes?
-Selectively permeable so controls substances going in and out.
-Maintains concentration difference of molecules on either side of the membrane.
-allows cell identification and adhesion
Which two organelles can only be found in animal cells?
Lysosomes and centrioles
Which 3 organelles can only be found in plants?
Chloroplasts, Vacuole with tonoplasts and Cellulose Cell Wall
What are lysosomes?
Small vacuoles surrounded by a membrane formed by pieces of golgi apparatus pinched off the end.
What is the function of lysosomes?
Break down worn out organelles and digest material taken in via phagocytosis
What type of enzymes are within a lysosome?
What is the action of the lysosomes?
Material taken into cell by endocytosis and trapped in vacuole.
Lysosomes fuse with vacuole membrane and release digestive enzymes, breaking down the material.
What is the structure of centrioles?
Microtubules, lying at right angles to each other
Where are centrioles located?
Centrosome just outside nucleus
What is the fuction of centrioles?
Formation of spindle fibres during cell division
What is the function of a plant cell's vacuole with a tonoplast?
Water and sap storage
Look at picture of chloroplast and cover up parts
What are a chloroplast's functions?
Traps light energy and uses it to produces carbohydrates from CO2 and H20
May also store starch and lipid
How is a cellulose cell wall structured?
Composed of cellulose microfibrils
Totally permeable TO WATER
Has many plasmodesmata
What are plasmodesmata and what are they for?
Pores that allow cytoplasm of adjacent cells to connect enabling substances to pass between cells
What is the function of cellulose cell walls?
Stops cell bursting in dilute solution i.e. prevents osmotic lysis.
Provides mechanical strength and support.
What is a tissue?
A group of similar cells together carrying out the same function.
How are epithelial tissue structured?
Continuous layer lining internal/external body surfaces
No blood vessels but may have nerve endings
Sit on basement membrane
What is are the key properties of cuboidal epithelium?
Simplest form, cube shape and one cell thick
Where is cuboidal epithelium found?
Kidney tubules and liver
What are the key properties of columnar epithelium?
Those that line tubes that substances move through will have more cilia
Where can columnar epithelium be found?
How is squamous cell epithelium shaped and where are they found?
Flattened cells on basement membrane
Walls of alveoli
What are the three epithelial tissues?
What do microvilli do when on epithelial tissue?
Increase cell membrane surface area for absorption e.g. Small intestine
What are the functions for epithelium tissues that have:-
ATP for active transport e.g. Ileum
For digestion (small intestine)
Cilia to trap and move particles e.g. respiratory traction
How do you calculate magnification?
Image size divided by object size
How do you calculate conversion factor?
Stage micrometer units divided by eyepiece units x 10
What are the three muscle tissue types?
What are the four properties of striated/skeletal muscle tissue?
What are the four properties of cardiac muscle tissue?
What are the three properties of smooth muscle tissue?
What is the purpose/location of striated/skeletal muscle tissue?
Connected to skeleton for movement
What is the purpose/location of cardiac muscle tissue?
What is the purpose/location of smooth muscle tissue?
Non skeletal muscle like diaphragm
What 3 things make up connective tissue?
What is the example of connective tissue?
Collagen (secondary fibrous protein)
What do fibroblasts do?
Provide structured framework for many tissues
-most common cells of connective tissue in animals
What are organs?
A group several tissues joining to carry out a particular function for the whole organism
What is cytoplasm?
Gel-like substance that contains cell's organelles
Whst is the structure found in all prokaryotes but not eukaryotes?
Mesosome- increases surface area
What four structures are only found in bacterium?
What makes up viruses?
DNA or RNA enclosed in a protein coat (matrix). Contain no cytoplasm.
What are the two DNA differences between eukaryotes and prokaryotes?
Prokaryotic has no organised nucleus with DNA free in cytoplasm and DNA circular whereas eukaryotic are bound by nuclear membrane and are linear strands (chromosomes)
What are the two cell wall differences between eukaryotes and prokaryotes?
Prokaryotic has a protective slime capsule and is made of murein, eukaryotic has none and a cellulose cell wall
What are the two internal and external size differences between eukaryotes and prokaryotes?
Prokaryotic have smaller ribosomes (70s) and smaller over all size (10um) compared to 80s and 100um
What is the site of respiration between eukaryotes and prokaryotes?
Prokaryotes' is foldings of cell membrane called mesosomes whereas eukaryotic's is mitochondria