cells and organelles
cells are the basic building blocks of life
they can replicate independently
they are the cells that make up an organism
there are multiple types of cells including
animal and plant cells
organelles are
cell membrane
control what goes inside and outside of the cell
a semi-permeable phospholipid bilayer
nucleus
contains the genetic material / dna of the cell
cytoplasm
a jelly like substance where the other organelles sit inside of
where the chemical reactions take place
mitochondria
provide cells with the energy needed to function
they break down sugars or glucose in aerobic respiration
ribosomes
site where protein is synthesised inside the cell
extra organelles in plant cells
cell wall
a hard wall around the cell made up of a material called cellulose
provides support and structure
vacuole
a sac inside the cell that contains cell sap (sugars, salts and water)
also found in the animal cell but in smaller proportions
chloroplasts
where photosynthesis happens
it produces a green substance called chlorophyll to absorb light energy
perixisome
the break down fatty acides and detoxify harmful substances
amyloplast
the synthesise and store large amounts of starch granules
granules
these primarily storage organelles
golgi vesicle
these bud off the golgi apparatus to modify, package, and transport proteins and lipids
extra organelles in the animal cells
lysosome
the are membrane-bound organelles that contain hydrolysis enzymes / acid hydrolase
the break down macromolecules
endoplasmic reticulum
rough
it is studded with ribosomes
it synthesises and folds proteins destined for secretion, cell membrane insertion, or lysosomes
smooth
lacks ribosomes
functions in lipid synthesis, steroid hormone production, detoxification and carbohydrate metabolisation
golgi apparatus
it modifies, sorts and packages proteins and lipids received from the endoplasmic reticulum into vesicles for delivery to lysosomes
nuclear membrane
it protects a eukaryotic cell’s genetic material by separating it from the cell membrane
centriole
organises microtubules during cell division to form mitosis spindle for chromosome seperation
centrosome
to organise the microtubules
microtubules
the provide structural support for intercellular transport of vesicles and organelles
bacterial cells
they are prokaryotic cells
this means they do not have a nucleus or membrane-bound organelles
the organelles are covered by the cell envelope (multiple layers of walls)
cell wall
protect the bacteria
it consists of peptidoglycan, which differentiates if bacteria is gram positive or gram negative
gram positive have a single thick layer of peptidoglycan above their cell membrane which allows the to retain staining dye
gram negative has a thin layer between the cell membrane and the plasma membrane
it also helps maintain the shape of the bacteria
the round bacteria is cocci, the rod shaped ones are called bacilli, appealed ones are spirilla and the ones with multiple forms are called pleomorphic
capsule
protects the bacteria against phagocytosis
it helps the bacteria adhere to surfaces
it is an important virulence factor (the power of a pathogen to cause disease)
plasma membrane
it encloses the cytoplasm (water, cell components, enzymes, molecules)
without the plasma membrane, the cell’s contents spill out
it acquires nutrients, eliminate waste and maintains constant organised state
it is selectively permeable, helps in respiration, photosynthesis and synthesis of lipids and cell wall components
ribosomes
sites of protein synthesis
they produce proteins that are destined to remain inside the cell
they can either be in the cytoplasm or attached to the plasma membrane
nucleoid
contains the cell’s chromosomes
the chromosomes are usually a single circle of double stranded DNA
some have a linear or more than one chromosome
plasmids
these are small double stranded DNA molecules that can exist independent of any chromosomes
they can be circular or linear
they have few genes and their genetic information is not important to the bacteria
the contain genes that can confer selective advantage to the bacterium (antibiotic resistance)
pili/fimbriae
these help the bacteria attach to surfaces
they are hair like structures on the bacteria’s body
when they are shorter they are called fimbriae, when they are longer pili
flagella
whip like protrusions that allow the bacteria to move
specialised cells
specialised cells are cells that have a structure that suits their function
the most common types of specialised cells are
the ciliated cells
these have hair-like projections called cilia that assisst in movement and transport
they move substances like mucus in the trachea and bronchi, ova in the fallopian tubes and cerebrospinal fluid in the brain
they have cilia, cell membrane, nucleus, mucus, cytoplasm and, mitochondria
root hair cells
these are epidermal cells at root tips with long, thin extensions that absorb water (osmosis) and mineral ions (active transport)
they lack chloroplasts, have a large vacuole and contain various mitochondria
they have a vacuole, mitochondria, nucleus, ribosomes, cytoplasm, root hair, cell wall and, cell membrane
palisade mesophyll cells
they are located on the upper epidermis of leaves
they have a high concentration of chloroplasts to assist in photosynthesis
the are oriented vertically to maximise light absorption and convert the light to carbohydrate
has a cell wall, cell membrane, cytoplasm, nucleus, vacuole and, chloroplasts
neurones
they are the cells responsible for receiving sensory inputs and for transforming and relaying the electrical signals
has a cell membrane, cell body, dendrites, axon hillock, myelin sheath, node of tannery, synaptic and bulbs, axon terminal, oligodendrocyte
red blood cells
they transport oxygen from lungs to body tissues
they contain haemoglobin that helps to transport oxygen
has a biconcave disc, cell membrane and haemoglobin
gametes
gametes are haploid cells that help in reproduction
sperm cells
the male gamete
it moves through substances using it’s flagellum
has a head, neck, nucleus and, flagellum
egg cells
the female gamete
fuses with the sperm cell to form an embryo
contains the corona, radiata, zona, pellucida, cytoplasm, and nucleus
definitions
cell - this is the smallest unit of all living organisms
tissue - a group of similar cells and extracellular matrix from the same origin that work together to perform specific functions in multicellular organisms
organ - it is a group of specialised tissues that work together as a functional unit to perform specific tasks in the body
organ system - a group of functionally related organs that work together to perform bodily functions
organism - any living thing that functions as an individual
size of specimens
to calculate magnification, you have to divide the observed size by the actual size of the specimen
to calculate the actual size of the specimen, you change the formula so you divide the image size by magnification
micrometers = 1000 millimetres, 10,000 centimetres, 1,000,000 metre