chapter 1 Flashcards
cell structure and organisation
how can we study the parts of the cell
(what type of microscopes)
- light
- electron
light microscpoes can magnify objects up to _ times
1000x
(one thousand times)
electron microscopes magnify objects to more than _ times
200 000x
(2 hundred thousand times)
what is the pictures called when a camera is fitted to either types of microscopes.
micrographs
difference between light micrographs and electron micrographs
- light, coloured but electron, black and white
- ultrastructure of cells is shown in electron but not light
- electron, 3D but light, 2D
what is a cell
The cell is the fundamental building block, the basic structural unit of all living organisms
basic unit of life
what are all cells made out of
- biological molecules such as
- nucleic acids
- proteins
- carbohydrates
- lipids
how do organelles work in a cell
while each organelle performs specific functions, the various organelles work as a co-ordinated system within the cell to carry out processes needed to sustain life.
what are organelles
a cellular structure that performs a specific job within a cell
2 types of cells
- prokaryotic
- eukaryotic
features of prokaryotic cells
- usually much smaller than eukaryotic cells.
- simpler internal structure without compartments
- lack true nucleus and membrane-bound organelles within the cell
- may have one or more plasmids
- no mitochondria
- cell wall is present
- have single circular loop DNA
what type of cells are all bacteria
prokaryotic cells
features of eukaryotic cells
- generally larger than prokaryotic cells.
- contain a distinct nucleus, have cytoplasm and a plasma membrane.
- have a compartmentalized internal cell structure and many membrane-bound organelles
- has numerous linear DNA strands
- no plasmids
- has mitochondria
- no cell wall(unless in plant cells)
eukaryotic cells occur in organisms such as
- algae
- protozoa
- fungi
- plants
- animals
all eukaryotic cells have_
- plasma membrane
- cytoplasm
- nucleus
what does every cell consists of
(10)
- plasma membrane
- vesicles
- cytoplasm
- nucleus
- rough endoplasmic reticulum
- ribosomes
- smooth endoplasmic reticulum
- golgi body
- mitochondria
- vacuoles
what do plant cells have that are not present in animal cells
- cell wall
- chloroplast (some plant cells)
what is a plasma membrane
selectively permeable bilayer membrane
what is a selectively permeable membrane
able to regulate the movement of substances according to the needs of the cell
what is partially permeable membrane
only allows smaller molecules to pass through but excludes larger molecules
where is the plasma membrane located
around cytoplasm
purpose of plasma membrane
- physical boundary between the cytoplasm of the cell and the external environment.
- controls the movement of substances entering and exiting the cell
what is a cell membrane
partially permeable membrane
where is the cell membrane located
(in/around the cell)
surrounds the organelles in the cell
what is cytoplasm
aqueous medium that contains many dissolved substances and enzymes
where is the cytoplasm located
(in/around the cell)
enclosed by the plasma membrane
purpose of cytoplasm
site where most cellular reactions occur
what does the nucleus contain
contains genetic information in the form of chromatin
what is the membrane surrounding the nucleus
nucleur envelope
(bound by a double membrane)
what does the nucleus do
control cell activities such as cell growth and repair of worn-out parts
why is the nucleus important
essential for cell division
(cells without a nucleus, red blood cell, are unable to divide)
what is the purpose of the nuclear membrane
separates the contents of the nucleus from the rest of the cytoplasm
what is needed to be able to see the individual parts of the nucleus clearly
electron microscopes
what does a chromatin contain
composed mainly of proteins and deoxyribonucleic acid
why is DNA important
contains all the genetic information that are essential for the survival of the cell
what happens when a cell is dividing
chromatin condenses into chromosomes.
what does DNA stand for
deoxyribonucleic acid
what is the function of the DNA
- carries herediatary information
- carries instructions that a cell needs for carrying out its activities
purpose of RER
synthesizes proteins and packeges them into vesicles for subsequent secretion
what does the rough endoplasmic reticulum (RER) consists of
a network of flattened spaces lined with a membrane
how does the surface of RER appear under a electron microscope
rough
why does the surface appear rough under a electron microscope
ribosomes are attached to its outer surface
the outer surface of the RER is _
continuous with the nuclear membrane
what are ribosomes
small round structures
where are ribosomes located
- attached to the membrane of the rough endoplasmic reticulum (RER)
- or lie freely in the cytoplasm
what do ribosomes do
needed to synthesise proteins in the cell
what do the ribosomes that are attached to the RER do
make proteins that are usually transported out of the cell or become part of the plasma membrane
what do the ribosomes that are lying freely in the cytoplasm do
make proteins that are used within the cytoplasm of that cell
what does the RER do with the proteins made by the ribosomes
transports proteins to the Golgi body for secretion out of the cell
what is the difference between smooth endoplasmic reticulum (SER) and rough endoplasmic reticulum (RER)
- SER does not have ribosomes attached to its membrane
- SER is more tubular than RER
what is the purpose of SER
- synthesizes substances such as lipids and steriods
- helps to detoxify drugs and poisons
what is the golgi body also know as
golgi apparatus
what is the golgi body shaped like
a disc
what does the golgi body consists of
a stack of flattened spaces surrounded by the membrane
what are secretory vesicles
tiny spherical spaces enclosed by a membrane that is connected to the plasma membrane
what does the golgi vesicles do
fuse with one side of the golgi body and pinching off the opposite side
what is the purpose of the golgi body
- chemically modifies substances made by the ER
- stores and packages these substances in vesicles for secretion out of the cell
what is step 1 to how substances made by the ER are moved out of the cell
- transport vesicles transport substances within the cell
- small vesicles containing substances made by the ER are pinched off from the ER
what is step 2 to how substances made by the ER are moved out of the cell
- these vesicles then fuse with the golgi body and release their contents into the golgi body
- the substances made by the ER may be modified inside the golgi body
what is step 3 to how substances made by the ER are moved out of the cell
- secretory vesicles containing these modified substances are pinched off from the golgi body
- they then move to the plasma membrane
what is step 4 to how substances made by the ER are moved out of the cell
the secretory vesicles fuse with the plasma membrane and their contents are released out of the cell
what is a mitochondrion
(mitochondria-plural)
- small oval or sausage shaped organelles
- numerous mitochondria present in cells with high energy requirements
(bound by a double membrane)
what occurs in the mitochondria
aerobic respiration where ATP is produced to power various cellular activities.
what does ATP stand for
Adenosine Triphosphate
what can the energy made during aerobic repiration be used for
may be used by the cell to perform cell activities such as growth and reproduction
what are vacuoles
a fluid-filled space enclosed by tonoplast (single, selectively permeable membrane)
what is the purpose of vacuoles
store substances within the cell
characteristics of vacuoles in plant cells
- large central vacuole
- contains cell sap
what is tonoplast
selectively permeable membrane surrounding the vacuole
(only for plant cell)
what does cell sap contain
- dissolved substances such as
- sugars
- mineral salts
- amino acids
characteristics of vacuoles in animal cells
- many small vacuoles
- contain food and water substances
- these vacuoles exists temporarily
what is a cell wall
fully permeable membrane
where is the cell wall located
(in/around the cell)
- encloses the entire plant cell
- surrounding the cell membrane
what is the purpose of the cell wall
- protects the cell from injury
- gives the cell a fixed shape
what is the cell wall made up of
cellulose
which cell is the cell wall absent
animal cells
what are chloroplasts
oval structures found in plant cells
(double membrane-bound organelle)
what do chloroplasts contain
green pigment called chlorophyll and other photosynthetic pigments
why is chlorophyll important
essential for photosynthesis
what is photosynthesis
the process by which plants make food
what is magnification
the number of times an image of an object is larger than the actual size
how to find the magnification
- magnification = image/actual object
- image = actual x magnification
- actual = image / magnification
1mm =
milimeter
1000μm
micrometer
1m =
1000mm
which part of the image should be measured
the longest width
what does a typical virus have
protein coat enclosing its genetic material
why are virus not considered a living thing
- lacks cellular structures
- does not move, grow, feed, respire or excrete
why are virus not considered a non-living thing
can reproduce
(but only when it enters a living cell)
features of virus cell
- protein coat (capsid)
- DNA/RNA
- no plasma membrane
- no cytoplasm
- no ribosomes
what does RNA stand for
ribonucleic acid
what are the vesicles in the cells
- golgi vesicle
- transport vesicle
- secretory vesicles
what is the levels of organization
- cell
- tissue
- organ
- organ system
- organism
