Cell Structure and Organisation Flashcards
What are all living organisms composed of?
One or more cells
What are cells?
The basic unit of life
What is the cell the fundament unit of ?
Structure
Function
Organisation
-In all organisms
What is the cell theory?
Cells can only arise from pre existing cells
What are the organelles of a generalised ultrastructure of an animal cell?
Centrioles
Mitochondrion
Lysosome
Rough endoplasmic reticulum
Nucleus
Smooth endoplasmic reticulum
80S ribosomes
Cell membrane
Cytoplasm
Secretory/golgi vessel
Golgi apparatus
What are the features of the nucleus?
Nucleolus
Chromatin
Nuclear pore
Nuclear Envelope( 2 membranes)
What is an organelle?
a specialised structure inside a cell with specific functions
What are the organelles of a generalised ultrastructure of a plant cell?
-Plasmodesma
-middle lamella
-Vacuole
-SER
-Plasma membrane(pressed against cell wall)
Ribosomes
Ribosomes
Nucleus
RER
Chloroplast
Cytoplasm
Golgi apparatus
Golgi Vesicle
Mitochondrion
What does the vacuole consist of?
Tonoplast
Cell sap
What does the chloroplast consist of?
grana
envelope
What do the measurements measure?
Km-ecosystem
m- larger organisms
mm- tissues
um- cells and organelles
nm- molecules/viruses
What is the purpose of microscopy?
to magnify small objects such as biological specimens mounted on glass slides
What are the features of a light microscope?
Objective power lens(4,10,40,100x)
Stage clips
Stage
Diaphragm
Light source
Base
Eye piece
Arm
Fine and course focus
Adjuster to move stage
Power cord
What is the power of the eyepiece lens?
10x
What is the power of the low power objective lens?
x4 (total magnification x 40)
what is the power of the medium power objective lens?
x 10 (total magnification x100)
what is the power of the high power objective lens?
x40 (total magnification x400)
how do you calculate the total magnification of microscope lens?
eyepiece x objective
why must the sample be thin when preparing it to view under microscope?
To allow light to pass through
why must a sample be stained to be viewed under a microscope?
So structures can be seen clearly, and adds contrast
Why might staining be a disadvantage when preparing a sample to be viewed under a microscope?
Stain could be toxic/harm or killed the organism
What is the nucleus and what is its function?
-largest organelle in the cell
-function is to retain the genetic information (DNA) which codes for protein synthesis
what is the nucleus surrounded by?
A double membrane (nuclear envelope)
What is the nucleus made up of?
nuclear envelope
Nucleoplasm
Chromatin
Nucleolus
What is the nuclear envelope?
-A double membrane (outer and inner) with nuclear pores to allow the transport of mRNA and ribosomes out of the nucleus to the cytoplasm
what is nucleoplasm?
cytoplasm like material within the nucleus, which contains chromatin
What is chromatin and what does it do?
-Made up of coils of DNA, bound to histone protein.
-During cell division, the chromatin condenses to form the visible chromosomes
What is the nucleolus and what does it do?
-small, spherical body (one or more within the nucleus)
-They synthesise ribosomal RNA
-Site of ribosome production
what is the structure of mitochondria?
usually oval shape, bound by a double membrane (envelope) with a narrow fulfilled intermembrane space
What is the function of the mitochondrion?
To release an energy in the form of ATP during aerobic respiration
what forms extensions called cristae?
-The inner membrane of the mitochondria is folded inwards
what does the cristae do?
The cristae increases the surface area for ATP to occur
Where is the matrix found?
Inside the mitochondrion
what is the organic matrix?
-contains many chemical compounds, including lipids, proteins, small (70S) ribosomes, and a small circle of DNA to allow self replication in response to the energy needs of the cell
-Where all chemical reactions take place
Where do the stages of aerobic respiration occur in the mitochondria?
In the matrix and on the inner membrane
Where are large numbers of mitochondria found
In the liver and muscle cells
How am mitochondria adapted to perform their function?
-largest surface area to volume ratio: increased gas exchange
-cylindrical: decreases distance for diffusion
-Folding of inner membrane/cristae- increased SA for enzymes/ more release of energy
What are ribosomes?
site of protein production
What are the small sub unit and large sub unit made of?
rRNA and protein
What occurs in the ribosomes?
Protein synthesis- mRNA from the nucleus fits into the groove between the 2 subunits and provides the code for a sequence of amino acids
Where are ribosomes found in a cell?
Free in the cytoplasm or associated with RER
What is the Rough Endoplasmic Reticulum?
an internal system of flattened membranous sacs, or cisternae, which are continuous with the nuclear membrane
What is the RER covered in?
Ribosomes
(gives it its name)
What the function of the RER?
protein synthesis and transport of proteins (polypeptide made by ribosomes), so it is present in large numbers in cells that synthesise large quantities of protein
What is the SER?
similar instructor to the RER has no ribosomes, hence its name
what is the SER involved in?
The synthesis and transport of lipids
What cells have extensive endoplasmic reticulum?
cells that store large quantities of carbohydrate, protein or fat (including liver and secretory cells)
what is the Golgi body made up of?
interconnected flattened membranous sacs
what fuses with the Golgi body?
Vesicles containing polypeptides pinch off from the RER and fuse with the gorge body
What happens when the verticals and the Golgi body fuse?
here proteins are modified and packaged into the vesicles, at the end of the Golgi body, Vesicles containing modified proteins bud off
What are the golgi’s main functions?
-Modifying and packaging proteins (e.g. enzymes) into secretory vesicles for secretion from the cell
-producing glycol protein
-Forming lysosomes
what does the Golgi body also have a role in?
-transporting and storing lipids
-Secreting carbohydrates, e.g for formation of plant cell walls
what are lysosomes?
Single membrane, bound vesicles that contain hydrolytic (digestive) enzymes
What are lysosomes produced by and what do they do?
They are produced by the Golgi body and isolate, potentially harmful digestive enzymes from the remainder of the cell
what are the functions of lysosomes?
-They release, hydraulic enzymes when the cell needs to breakdown, worn out organelles
-they digest material that has been taken into the cell. For example, lysosomes fuse with the vesicle made when a white blood cell engulf bacteria by phagocytosis, and there enzyme digest the bacteria.
The synthesis and secretion of protein is from the cell—>
- The nucleus contains the DNA which is copied (during transcription) to produce MRNA.
2.Nuclear pores in the nuclear envelope allow mRNA molecules to
leave the nucleus and attach to ribosomes in the cytoplasm or on the RER. - Protein synthesis occurs on ribosomes (which are composed of rRNA and protein and synthesized in the nucleolus).
- Poly peptides are moved through the RER and are packaged into vesicles. The vesicles bud off the RER and carry the polypeptides to the Golgi body.
- The vesicle fuses with the membranes and shed its contents into the Golgi apparatus. Here the protein is modified.
6.At the other end of the Golgi body, vesicles containing the modified proteins bud off. - They may be secretory vesicles., which carry the proteins to the cell
membrane for secretion by exocytosis. Alternatively these may be
lysosomes containing digestive enzymes which will be used within the cell
What is the list of organelles involved in the synthesis and secretion of proteins from the cell in order?
nucleus
nuclear pore
ribosomes
RER
Golgi body
secretory vesicle
cell membrane
what are all cells surrounded by?
A cell surface membrane or plasma membrane
What are the principal biochemical components (cell membrane)?
phospholipid and protein molecules
how are the phospholipid molecules arranged in a cell membrane?
arranged as a bilayer, with one sheet of phospholipid opposite another
what is actual width of the cell membrane?
7-8 nm
What are the structural components of the membrane?
phospholipids
proteins
Carbohydrates
Cholesterol
what do phospholipids form?
bilayers with hydrophilic, heads, pointing outwards, interacting with the tissue fluid/blood plasma that surrounds the cell, and the cytoplasm in inside the cell
what is the structure of a phospholipid
-Phosphate group (polar head hydrophilic)
-Ester Bond
-Fatty acid (non polar, hydrophobic)
Why do the hydrophobic tails of both layers in the phospholipid point towards the inside of the membrane?
-The tails, repel water present in the side of plasm and extra cellular fluid, and the heads are attracted to this water
what do cell membranes appear as when viewed under the electron microscope?
As a double line
why does the dye used to stain cell membranes associate with the hydrophilic phospholipid heads?
it is a water soluble dye
(phospholipid heads appear dark)
What are all proteins in the membrane?
Globular
where on the cell membrane can proteins be found?
on the surface of the bilayer or partly embedded (extrinsic) or extending completely across both phospholipid layers (intrinsic/transmembrane)
describe and explain the position of the charged or hydrophilic parts of the protein in relation to the phospholipids—
-Charged parts of the protein are attracted to the phosphate heads
-uncharged parts of the protein associate with the nonpolar fatty acid tails of the phospholipids
Where are carbohydrates found?
-they are found only pointing out of the outside of the cell attached to either the proteins (glycoproteins), or attached to the phospholipids (glycolipids)
what is cholesterol present?
Between the phospholipids in animal cell membranes
what is the name of the cell membrane structure?
The fluid mosaic model
What are the components associated with the fluid mosaic model?
-hydrophilic head
-Extrinsic protein
-Hydrophilic pore
-Hydrophobic tails
-Intrinsic protein
-Glycoprotein
-Phospholipid bilayer
-Channel protein
-Carbohydrate
-Glycolipid
Why does the fluid mosaic model have its name?
fluid- the individual phospholipid molecules, give around relative to one another
-Mosaic- the proteins embedded in the bilayer of vary in size and shape and arranged in a random pattern
What is the main function of the cell membrane?
-to aid transport of certain substances into/out of the cells- w.g. To obtain and remove carbon dioxide.
What are phospholipids?
Former selective bilayer that allows nonpolar or uncharged molecules through, but prevents the passage of polar or charged molecules
what are extrinsic proteins?
associated with one layer only. May act as receptors for hormones.
what are intrinsic proteins?
-Act as cell to cell recognition- e.g. White blood cells in an immune response.
-Also important in cell adhesion and acting as receptors
what is glycocalyx?
-Act as carriers or channels to allow the passage of charged or polar molecules such as glucose
what is cholesterol?
-Controls membrane fluidity
where are centrioles found?
in the cells of all animals are most protoctists, but not in the cells of higher plants (they are located just outside of the nucleus)
What do centrioles consist of?
-Two rings of microtubules arranged in hollow cylinders positioned at right angles to one another
what happens to centrioles during cell division?
they migrate to opposite poles of the cell, and inform the spindle
what type of vacuole do most plant cells have and what do these consist of?
-large permanent vacuole, which consist of a fluid filled sac bounded by a single membrane, the tonoplast
what does cell sap (vacuole) contain?
Salsa is a mineral, which does chemicals such as glucose, amino, acids and vitamins
what do vacuoles have a major role in supporting?
Soft plant tissues
What are vacuoles like in animal cells?
-they are small temporary vehicles and may occur in large numbers
-They can be formed by phagocytosis
What is the plant cell wall made up of?
-cellulose microfibrils embedded in a polysaccharide matrix called pectin
what do you cell walls do?
confer rigidity (strength) on plant cells
what is plasmodesmata?
narrow pores in the cell wall
what happens at the plasmodesmata?
-find strands of cytoplasm pass through these, connecting one cell to the next, and allowing substances to move between them
where are chloroplasts found?
-only in plant cells- each has a double membrane
What is found within the chloroplast?
-A colourless gelatinous matrix called the stroma
What does the stroma contain?
small (70s) ribosomes, circular dna belonging to the chloroplast (for self replication), lipid and starch grains
what are in the stroma?
-flattened sacs known as thylakoids
-these are stacked to form grana (single granum) connected to each other by lamellae
what are found within each thylakoid?
Photosynthetic pigments such as chlorophyll
what components are found in the chloroplast?
-double membrane
-outer membrane
-thylakoid desk
-Stroma
-Granum
-Starch
-Inner membrane
-Circular DNA
-70s ribosomes
what is the endosymbiotic theory state?
-that organelles such as chloroplasts and mitochondria, were originally free living prokaryotic cells
-A hypothesis states that these prokaryotic cells were engulfed by itself through endocytosis, gaining an additional membrane
-for the prokaryote formed a mitochondrion- it would have gained protection and glucose from the cell and the cell gained ATP from the prokaryote
-Eventually, this prokaryote formed the mitochondrion inside the cell (mitochondria and chloroplast do contain their own DNA)
what are the structures found in only plant cells?
-Cellulose cell wall with plasmodesmata
-Chloroplasts
-Large permanent, vacuoles
What structures are found in only animal cells
-centrioles and centrosomes
-small vacuoles
what structures are found in both animal and plant cells?
-plasma membrane
-Endoplasmic reticulum
-Mitochondria
-Nucleus
-Golgi body
-Ribosomes
-cytoskeleton
-lysosomes
what are eukaryotes?
Organisms made of cells that have membrane organelles with DNA within the nucleus in the form of chromosomes
What are prokaryotes?
-Single, celled organisms, lacking membrane bound organelles, such as nuclei with DNA free in the cytoplasm
What are the components in a prokaryote?
-DNA
-Ribosomes (site of aerobic respiration)
-Flagellum
-Plasmid
-Cell Wall
-Cell membrane
-Slime coat of bacteria
what are viruses described as?
-acellular, as they are not made of cells
why can’t viruses be seen through a light microscope?
they are a so small
why can’t viruses carry out protein synthesis?
they do not have organelles, so they don’t have ribosomes
why can’t viruses replicate nucleic acids?
They don’t contain enzymes
why viruses only reproduce inside the host cell?
because they don’t have enzymes or organelles, so they hijack the host cells metabolism i.e. using the host cells organelles and enzymes.
What else do viruses not contain?
chromosomes
what is each virus made up of nucleic acid surrounded by?
-A protein coat (the capsid).
What do viruses contain?
Some devices have DNA while others contain RNA
what are bacteriophages?
Viruses that attack bacteria
what are the components of a virus?
-Envelope
-Lipid capsule
-protein coat (caspid)
-DNA or RNA
-Nucleic acid
What can viruses be transmitted by?
-Aerosol
-Insect vectors
-Exchange of bodily fluids
-Bites
What are bacteriophages?
viruses which inject bacteria such as Escherichia coli
what are the difference between normal viruses and bacteriophages?
They have DNA, where is normal viruses tend to have RNA inside them
What infectious diseases do viruses cause?
-Human- Flu, chickenpox, HIV, mumps, rubella, Ebola
-Plants- tobacco mosaic virus
-Birds- Avian flu
-Other mammals swine flu, cowpox, feline leukaemia virus
What is the definition of an organism?
All systems of the body working together, make an organism which is a discrete individual
what are the levels of organisation in the human body?
Cells
Tissues
Organs
Organ systems
What is unicellular?
Single celled organisms which carry out life functions within one cell
What is multicellular?
organisms, consisting of many specialised cells, which form tissues and organs, which have various structures and roles
What is division of labour?
-The adaption of different parts of an organism to carry out different functions
-The more advanced the organism the greater to the division of labour
What is differentiation?
The process, by which a stem cell becomes specialised in a specific type of cell
What is the first level of organisation?
cells-
-Red blood cell
-ovum cell
-Sperm cell
-Neurone
-intestinal epithelial cell
What is a tissue?
an aggregation of specialised cells, carrying out a specific function
What are the 4 primary tissues types in the body?
-epithelial tissue
-muscle tissue
What do epithelial tissues form?
a continuous layer, covering or lining the internal and external surfaces of the body.
What are the four types of epithelial tissues?
-Squamous Epithelium
-Cuboidal Epithelium
-Columnar Epithelium
-Ciliated Columnar Epithelium
what is squamous epithelium?
Flattened cells found lining body cavities, such as the mouth and alveoli
What’s is cuboidal epithelium?
Cube-shaped cells found lining the kidney tubules and ducts of glands
What is columnar epithelium?
Elongated column-shaped cells that are found lining the stomach and intestines
what is ciliated columnar epithelium?
Column-shaped cells tha have fine hair-like projections (cilia) on the surface, e.g. in the trachea, oviduct
What does connective tissue do?
connects and anchors structures and gives strength and support to the body and its organs.
what does collagen protein form?
extracellular fibres that give strength to dense connective tissues such as the tendons and ligaments
where is also collagen found?
In the tough layer of large blood vessels
What is muscle tissue?
-nerve impulse spring about muscle contraction, causing the muscle to shorten
-As contraction of the muscle ends, normal muscle length is once again attained
what are examples of muscle cells that create muscle tissue?
-muscle cell (heart)
-Skeletal muscle cell (bones)
-smooth muscle cell (stomach- covers delicate organs)
What are organs?
An aggregation of several tissues that carry out a specific function for the whole organism.
What are organ systems?
Two or more different organs working together to provide a common function.
What are the major organs in the skeletal system?
Bones, cartilage, tendons, ligaments
what major role does the skeletal system have?
support
What major organs make up the muscular system?
Skeletal and smooth muscle
what is the major role of the muscular system?
movement
What organs are found in the circulatory system?
heart, blood vessels, blood
What is the major role of the circulatory system?
Transport of gases and nutrients
what major organs are included in the reproductive system?
Ovaries, uterus, oviducts, vagina Testes, penis, seminal vesicles
What is the major role of the reproductive system?
Reproduction
what major organs are included in the endocrine system?
Glands, e.g. thyroid, pituitary, adrenal
what major role does the endocrine system have?
Homeostasis
What major organs are included in the excretory system?
Kidneys, bladder, ureters, urethra
What is the major role of the excretory system?
Removal of waste
what major organs are included in the digestive system?
Oesophagus, stomach, intestines, liver, pancreas
What is the major role of the digestive system?
To breakdown, food and absorb nutrients.
what major organs are included in the nervous system?
Brain, spinal cord, peripheral nerves
What is the major role of the nervous system?
Coordination and control.
what major organs are involved in the respiratory system?
Lungs, diaphragm
What is the major role of the respiratory system?
To exchange, gases between blood and air
What major organs are involved in the immune system?
Lymph, white blood cells
What is the major role of the immune system?
Protection from pathogens
what are the levels of organisation in plants?
-Cells
-Tissues
-Organs
what are examples of some specialised plant cells?
-Palisade Mesophyll
-Guard Cells
-Root Hair cell
What are tissues in plants?
-xylem
-phloem
-Palisade mesophyll
-Spongy mesophyll
-upper epidermis
what is the function of the xylem?
transport of water and dissolved minerals
What is the function of the phloem?
Transport of sucrose and amino acids (photosynthates)
What is the function of the palisade mesophyll?
photosynthesis
what is the function of the spongy mesophyll?
Some photosynthesis, this tissue provides air space for diffusion of gases in/out of the leaf.
What is the function of the upper epidermis?
Contains cells that are found on the top surface of a leaf; protected by a waterproof waxy cuticle
What are plant organs?
-flower
-leaf
-stem
-roots
What is the function of a flower?
Sexual reproduction
What is the function of a leaf?
Photosynthesis
What is the function of a stem?
Transport and support
What is the function of the the roots?
-water and mineral uptake
-Anchorage
What is the definition of chromatin?
Coils of DNA, bound to histone proteins
