Cell biology Flashcards
Animal cell contents
Lysosome, golgi body, mitochondria, centriole, ribosomes, RER, cell membrane, nuclear pore, nucleolus, chromatin, nuclear envelope, vesicle
Plant cells content
Nucleolus, vacuole, cell wall, cell membrane, mitochondria, chloroplast, golgi body ribosomes, cytoplasm, nucleus, SER, plasmodesma, nucleus pore and envelope, tonoplast
nucleus
Contains DNA codes for protein synthesis- Site of transcription
DNA also provides templates for DNA replication
Bounded by two membranes- envelope, pore: Allows passage of large molecules eg. Mrna
outer membrane is continuous with endoplasmic reticulum
Within the nucleus
Granular material in nucleus is nucleoplasm containing chromatin- made of coils of DNA bound to protein during cell division.
condenses into chromosomes
Within the nucleus are 1 or more small spherical bodies called nucleolus
mitochondria content
Matrix, outer membrane, inner membrane space, inner membrane, 70S ribosomes, cristae, DNA
Function of mitochondria
produces ATP in aerobic respiration
Inter membrane space- mitochondria
2 membranes separated by a narrow, fluid filled inter membrane space
Inner membrane is folded inwards to form cristae
organic matrix- mitochondria
definition
solution containing compounds eg. Lipids, proteins
Circle of DNA- mitochondria
So mitochondrion can replicate and code for some of its proteins and RNA
70s ribosomes- mitochondria
allows protein synthesis
Functions of features- mitochondria
Some reactions occur in the matrix and other in the inner membrane
Christie provides large service area for attachment of enzymes involved in respiration
Cylinder shape reduces diffusion distance between the edge and the centre- Making aerobic respiration more efficient
muscle cells contain lots of mitochondria as they require more energy for frequent relaxation and contraction
function of chloroplast
Occur in the cell of photosynthesizing tissue
Chloroplast content
Each chloroplast is surrounded by two membranes comprising chloroplast envelope
Stroma- Fluid filled containing some products of photosynthesis
70s ribosomes and circular DNA- Enable them to make some of their own protein and self replicate
within the stroma
- flattened sacs called thylakoids
- stack of them called granum’s
-chlorophyll found in thylakoids - arrangements produces large SA efficient for trapping light energy
Endoplasmic Reticulum
Parallel double membranes forming flattened sacks with interconnected fluid filled spaces between them- cisternae
rough ER (RER)
Has ribosomes on the outer surface transporting proteins made there
80s manufacturers and transport proteins
smooth ER (SER)
Comprises membranes that lack ribosomes, associated with transportation and synthesis of lipids
ribosomes
1 large and 1 small subunit
Assembled in a nucleus from rRNA and protein
Involved in protein synthesis
70s found in bacteria and mitochondria
80s in RER
Golgi body function
processes and packages proteins
Golgi body features
vesicles- contain polypeptides, pinch off RER fusing with stack of membranes, which constitute the golgi body
At the other end of the Golgi, vehicles containing modified proteins are pinched off.
May carry proteins elsewhere in the cell or move to and fuse with the cell membrane, secreting modified proteins by exocytosis
Lysosomes
Small temporary vacuole surrounded by a single membrane- Formed by being pinched off from the golgi body
Lysosome functions
Contain and isolate potentially harmful digestive enzymes from the remainder of the cell
Get rid of all damaged organelles by surrounding and digesting them
Digest material taken into the cell
Involved in cell death
Eg. They fuse with a vesicle when white blood sell engulfs bacteria by phagocytosis and their enzyme digest bacteria
Centrioles- in animal cells
Located just outside the nucleus
Two rings of microtubules make hollow cylinders positioned at right angles to one another
centriole function
Cell division- Centrioles organised microtubules to make the spindle
Vacoule
Fluid filled sac
Bounded by a single membrane- tonoplast
Contain sap
vacuole function
maintains turger your pressure and keeps the cell firm
Cell wall
Consists of mostly cellulose- Held together in microfibrils
Microfibrils are arrogated into fibres, embedded in polysaccharide matrix- pectin
Cell wall functions- transport
Gaps between cellulose fibres make cell wall fully permeable to water and solvents Outside cell called Apoplast
Apoplast pathway- main way water crosses plant root
cell wall functions- mechanical strength
structure of microfibrils and laminated arrangement makes cell wall very strong
When vacuole is full of solution, cell content push against the cell wall- resisting expansion and cell becomes turgid supporting the plant
cell wall functions- communication between cells
Has pits which strands of cytoplasm (plasmodesmata) pass
Occurs when no cellulose is present to thicken between 2 cells
Strands run from 1 cell to the next
differences in plant & animal cells
cell wall, chlroplast, plasmodesma, vacuole, centrioles,enedgy store
cell wall:
A- absent
P- present, surrounds cell membrane
Chloroplast:
A-absent
P-present, in cells above ground
Plasmodesmata:
A- absent
P- present
Vacuole:
A-present, small temperory scattered throughout cell
P- present, large permanent,cell sap
Centrioles:
A- present
P- absent from higher plant cells
Energy store:
A- glycogen
P- starch
organelles are interrelated
- Nucleus contains chromosomes- DNA codes proteins
- Nuclear pore in nuclear envelope allows mRNA molecules, transcribed in DNA, to leave nucleus and attach to ribosomes in cytoplasm
- ribosomes contain rRNA transcribed from DNA in nucleolus
- Protein synthesis on ribosomes, produce primary structure proteins
- Polypeptides on ribosomes move through RER- packaged into vesicles
- Vehicles bud off R E R carrying polypeptides to golgi body- Modified unfolded
- Golgi body produces vehicles containing newly synthesised proteins eh. Lysosomes, secretory vesicles to carry proteins to cell membrane
- Phospholipids and triglycerides move through SER to various areas in the cell
Prokaryotic cells: Bacteria
no nucleus
Rarely form multicellular structures- unicellular
In all prokaryotes
- DNA molecule loose in cytoplasm
- Peptidoglycun (murein)
-cell wall
-70s ribosomes - cytoplasm
- cell membrane
in some prokaryotes
- Slime coat
- flagella
- Photosynthetic lamellae holding photosynthetic pigments
- Mesosome, possible site for aerobic respiration
Differences between P and E cells
Length, organelles, dna. Nuclear envelope, cell wall contents , plasmids chloroplasrs, mitochondja, mesosome, ribosomes
length:
P- small 1-10 mm
E- larger 10-100 mm
Organelles:
P- none
E- membrane bound
DNA:
P- free in cytoplasm
E- combined w protein in chromosomes
Nuclear envelope
P- none
E- double membrane
Cell wall
P- peptidoglycan (murein)
E- cellulose, chitin
Plasmids:
P- may be present
E- absent
Chloroplasts:
P- none,photosynthetic lamellae
E- in some plants
Mitochondria:
P- none,mesosome
E- present
Mesosome:
P- in some
E- absent
Ribosomes:
P- 70s, free in cytoplasm
E- 80s, free in cytoplasm, attached to ER
Viruses
- Small, pass through filters trapping bacteria
- acellular
- no organelles, cytoplasm, chromosomes
- outside cell, Virus exists as an inert vision
- each virus is made up of core of nucleic acid, surrounding protein coat
- bacteriophage virus attack bacteria
- crystalised, only reproduce
- Take over cells metabolism and multiply inside
Level of organisms
Differentiation: development of cells
CELL- Smallest self supporting unit of living things
TISSUE- Group of more or less similar specialised cells working together with a common purpose
ORGAN- A group of different tissue working together with a common purpose
ORGAN SYSTEM- Group of several different organs working together for a major body function
Epithial tissue
Forms continuous layer, covering or lining of the body surface
No blood vessel, may have nerve ending
Basement membrane: collagen and protein
Protects organs (peritoneum)
Secretory (lining of gut, salivary gland)
Absorptive (small intestine lining)
Types of tissue
Epithelial- covering tissue
Connective- Cells with extracellular material connects organs
Muscle- Contractile tissue
Nervous- electrical tissue
cuboidal epithial
One cell thick
Found in proximal convoluted tubular of kidney nephron and salivary gland ducts
squamous epithelial
Thin flattened cells
Found in thin layer surfaces allowing diffusion
Forms walls on alveoli and line the Bauman’s capsule of Nephron
Low friction linings eh. Peritoneum
columnar epithelial
Tall elongated cells
Functions:
Mechanical- Support structure eg gall bladder
Secretary- Lots of Golgi to modify proteins eg thyroid gland
Absorptive- Small intestine
specialised columnar epithelial
Micro Villi increase surface area for absorption
Goblet cells make mucus to line the tissue
Cillia creates movement
Connective tissue
connects, supports or separates tissue and organs
Contains elastic and collagen fibres in an extracellular fluid/ matrix
Between fibres are fat storing cells (adipocytes) and cells of immune system
Cardiac muscle
found in the heart
Same striations- lack long fibres of skeletal
Contract rhymically without any stimulation- doesn’t tire/ cramp
Skeletal muscle
Voluntary/ striated muscle
Bonds of long cells/ fibres
smooth muscle
contracts rhymicaly, occur in blood vessel walls
Involuntary muscles, unstriated
Plant tissues
Packing- fill bulk of stem, root, leaf
Supporting - cell with strong thick wall, support plant
Vascular - xylem, pholem: Vascular bundles
Protective - protects plant
xylem
Transport water and minerals from roots
Thickened Angular Wars called vessels line up on top of each other
No cytoplasm
Water moves through cavity
pholem
Transport sugar from leaves to stem and roots
Smaller and less thickened walls
Line up to form long pipes
End walls of cells have perfarations
calculation conversions
1000nm= 1 micron
1000 micron= 1mm
1000mm= 1m
1000m=1km
1cm=10mm
artifact
Man made distortions and defects
Types of microscopes
Light microscope
Transmission Electron microscope
Scanning electron microscope
what causes artifacts
Harsh chemicals and treatments
TEM
Electrons pass through thin sections and dense tissue absorbs more electrons
It allows to see the ultra structure of a cell
Less dense, less absorbing
Section through the cell in 2D
SEM
Detailed image of surface structure
Higher magnification and resolution
Samples must be dead because used in vacuum
Harsh fixatives
3D
Why is a vacuum created in the column
Electron beams are so thin that electrons in the air can block or defect the beam
function of a microscope
View cells that can’t be seen by the naked eye
magnification
Degree to which size of object is enlarged
Resolution
Degree to which is possible to distinguish between two objects which are very close together
light microscope
No harsh chemicals used
can see living cells
Low resolution and magnification
use of stain
contrast
Vibrations in microscope
The microscope must be very stable as vibrations will deflect the beam
gold in electron microscope
Reflects images/ objects
electron microscope
Greater magnification resolution
Uses harsh chemicals therefore specimen is dead
