CELLS Flashcards
cell function
is the building block of structures in living things.
how are cells derived
cell division.
what does the information in cells do
is used as instructions for growth, development and functioning.
what does protoplasm consist of
the nucleus, cytoplasm and cell surface membrane (plasma membrane).
3 things the nucleus consists of
1.Chromatin threads
2.Nucleolus,
3.Nucleoplasm,
Chromatin threads function
it contains hereditary material DNA. *They condense into chromosomes during cell division.
Nucleolus function
a spherical structure where components of ribosomes, essential for the formation of proteins, are synthesised and assembled.
What is nucleoplasm
it is dense protoplasm
what is the nucleus surrounded by
The nucleus is surrounded by a nuclear envelope, which is a double membrane perforated by nuclear pores.
2 nucleus function
- controls cell activities such as biochemical reactions, cell growth and repair.
2.It is essential for cell division. Nuclear division is the basis of cell division and reproduction, and thus continued survival of the organism.
cytoplasm vs cytosol
cytoplasm is everything in the cells besides the nucleus(e.g. cytosol, organelles)
cytosol is the semi-fluid liquid in the cell
mitochondrion function
the main site of ATP production in aerobic respiration.
mitochondrion shape
rod shaped or cylindrical
what are mitochondria bounded by
they are bounded by double membranes(both are phospholipid bilayer)
The outer and inner membranes are separated by the inter-membrane space.
mitochondria outer vs inner membrane
The outer membrane is a smooth continuous boundary while the inner membrane is extensively folded to form cristae which project into the semi-fluid matrix.
mitcondria DNA shape
circular
chloroplasts function
organelles where photosynthesis takes place
chloroplasts typical length
chloroplasts are large organelles, a few µm in diameter and 5-10 µm in length. (millimeter)
what surrounds the chloroplasts
surrounded by 2 membranes, whcih forms the chloroplast envelope
what does chloroplast contain
chlorophyll and other photosynthetic pigments called thylakoids(green) which are stacked to form grana(sing.granum)
what are stacks of grana joined by
intergranal lamellae.
what is the interior of a chloroplast filled with
a gel-like matrix called stroma. It contains soluble enzymes and circular DNA.
vacuole function
A large, central vacuole in a plant cell is a fluid-filled space enclosed by a membrane (tonoplast) that pushes the cytoplasm to the edge of the cell.
what is the liquid in the vacuole called
cell sap
what does the cell sap contain
The fluid (cell sap) in plant cells contains water, dissolved sugars, salts and amino acids.
can animal cells have vacuoles
Animal cells may contain many small, non-permanent vacuoles.
ribosome function
Ribosomes are sites where the cell makes proteins.
free vs bound ribosomes
Free ribosomes are suspended in the cytoplasm. They usually make proteins for use in the cell.
Bound ribosomes are attached to the membranous network called the endoplasmic reticulum and they usually make proteins for secretion from the cell.
what does endoplasmic reticulum contain
Endoplasmic reticulum (ER) consists of a network of flattened, membrane-bound sacs called cisternae (sing. cisterna).
where does endoplasmic reticulum originate from
the outer membrane of the nucleus, to which it oftens remain attached
rough vs smooth ER
Rough ER appears rough because ribosomes are attached to the outer surface. This is the site of synthesis of proteins which are packaged in membranous vesicles and secreted across the cell membrane.
Smooth ER lacks ribosomes. Smooth ER is more tubular than rough ER. Smooth ER is the site of synthesis of lipids such as fats and steroids and detoxification of harmful substances into harmless substances.
what does GOLGI BODY contain
stack of **flattened membranous sacs **also known as cisternae and a system of associated vesicles called Golgi vesicles.
golgi body function
receives proteins and lipids from the ER and **modifies them chemically **before sorting and repackaging them into secretory vesicles.
what do the secretary vesicles do
The secretory vesicles fuse with the cell membrane and release the secretory proteins, for example, enzymes, to the exterior of the cell via a process known as exocytosis.
LYSOSOME physical description
Lysosomes are spherical vesicles bounded by a single membrane.
what do lysosomes contain and its function
They contain digestive enzymes that can break down macromolecules such as proteins, polysaccharides, fats and nucleic acids. Macromolecules found in bacteria that have been engulfed by white blood cells are broken down by lysosomal enzymes.
what happens to the protein synthesised by the ribosomes
the polypeptide chain grows from the bound ribosome, it enters the cisternal space of the ER and folds into its native conformation.
the cell/plasma membrane is _____ _______
and is made up of _______ ________
selectively permeable
phospholipid bilayer
cis face function
receiving side of the golgi body. it receives newly synthesized proteins and lipids from the ER.
Transport vesicles carrying proteins and lipids from the ER fuse with the membrane at the cis face, delivering their cargo into the Golgi apparatus.
trans function
\ The trans face functions as the shipping side of the Golgi apparatus. It sorts and packages proteins and lipids into vesicles for transport to their final destinations, such as the plasma membrane, lysosomes, or secretion outside the cel
Secretory vesicles bud off from the trans face, carrying modified and sorted proteins and lipids to their target locations.
cytoskeleton
The cytoskeleton provides a structural framework, giving the cell its shape and stabilising membranous systems.
centrioles function
Centrioles play a role in nuclear division in animal cells.
what is Fluid mosaic model of membrane structure
the phospholipid bilayer
plasma/cell membrane
externally. It is a selectively permeable membrane that controls the type of substance that enters or leaves the cell.
what is the plasma membrane made of
The plasma membrane is composed mainly of lipids and proteins and known as the phospholipid bilayer.
what forms the bilayer and features of it
Phospholipid molecules form a bilayer. They have a hydrophilic (“water-loving”) and a hydrophobic (“water-hating”) end.
what forms the hydrophillic part of the phospholipid bilayer
The charged phosphate groups face outwards and interact with the aqueous environment on either side of the cell membrane, forming the hydrophilic part.
what forms the hydrophobic interior of the cell membrane.
The hydrocarbon chains of fatty acids of the phospholipid molecules face inwards and form the hydrophobic interior of the cell membrane.
peripheral vs integral proteins
peripheral proteins on the surface of the phospholipid bilayer
integral proteins which penetrate part of the way or all the way through the phospholipid bilayer.
why are Cell membranes are asymmetric,
Cell membranes are asymmetric, meaning that two halves of the membrane have different lipid and protein composition.
whazt does cell membranes being asymmetrical mean
Cell membranes are asymmetric, meaning that two halves of the membrane have different lipid and protein composition.
why are Cell membranes fluid structures
Cell membranes are fluid structures because the phospholipid molecules and some membrane proteins can move about in the plane of the membrane. The proteins are scattered throughout the phospholipid bilayer in a mosaic arrangement.
how do charged ions and polar molecules get across the phospholipid bilayer
Channel and carrier proteins are involved in transport of polar molecules and charged ions across the membrane
cell wall functions
A plant cell has a cellulose cell wall that encloses the entire plant cell. It protects the cell from injury and gives the cell a fixed shape. The cell wall is fully permeable, so it does not control the type of substances that enter or leave the cell.
what has prokaryotic cells
bacteria
what has eukaryotic cells
Protists, plants, fungi and animals
prokaryotic cells features
The prokaryotic cell has no distinct nucleus. Its genetic material (DNA) is concentrated in a region called the nucleoid, but no membrane separates this region from the rest of the cell. In contrast, a eukaryotic cell has a true nucleus enclosed by a membranous nuclear envelope. (nucleoid is js dna that floats around the cytoplasm)
6 similarities between plants and animals cells
1.Both have a cell surface membrane surrounding the cell.
2. Both have cytoplasm.
3. Both have a nucleus each.
4. Both contain mitochondria.
5. Both contain endoplasmic reticulum
6. both contain ribosomes.
which is larger
prokaryotic/eukaryotic
eukaryotic cellls are usually bigger
prokaryotic cells are extremely small
which has membranous structures
prokaryotic/eukaryotic
There is absence of membranous structures in prokaryotic cells, but eukaryotic cells have many organelles bounded by membranes.
5 differences between plant and animal cells
- Have a cellulose cell wall outside cell membrane/No cell wall
- Often have chloroplasts containing chlorophyll/No chloroplasts
- Often have a large central vacuole with cell sap/Only have small vacuoles
4.Centrioles are absent in higher plants/Two centrioles that play a part in cell division are present - Often have starch granules/Do not have starch granules; sometimes have glycogen granules
how do electron microscopes work
The electron microscope focuses a beam of electrons through very thin sections of a specimen.
how do cells get specialised(divisonoflabour in the cells
function of the root hair cell
The function of a root hair cell is to absorb water and dissolved mineral salts from the soil.
3 structural adaptions of the root hair cell
1, The root hair cell has a long and narrow extension / protrusion.
2. Each root hair cell contains many *mitochondria.**
3. The root hair cell has a large vacuole containing cell sap made up of a relatively concentrated solution of sugars and salts.
The root hair cell has a long and narrow extension / protrusion adaption function
The long and narrow protrusion of the root hair cell increases surface area to volume ratio for efficient absorption of water and dissolved mineral salts from the soil.
Each root hair cell contains many mitochondria adaptation function
More energy in the form of ATP molecules can be released for active transport for the absorption of dissolved mineral salts.
The root hair cell has a large vacuole containing cell sap made up of a relatively concentrated solution of sugars and salts. adaption function
The root hair cell has a more negative water potential than that of the soil solution. Water enters the root hair cell by osmosis across the selectively permeable cell membrane.
xylem vessels function
The function of xylem vessel is to transport water and dissolved mineral salts up the plant from the roots.
Xylem vessels are made up of long cells joined end to end. End walls (cross walls) between adjacent cells are broken down. adaptation function
Adjacent cells joined end to end allow for a continuous flow of water and dissolved mineral salts up the plant.
3 xylem vessel adaptations
- Xylem vessels are made up of long cells joined end to end. End walls (cross walls) between adjacent cells are broken down.
- There is absence of protoplasm in the xylem vessel. Thus mature xylem vessels are non-living.
3.There is deposition of lignin, a tough substance, on its inner wall (cellulose cell wall).
what is a virus made of
A viral particle is made up of a central core of **nucleic acid* (deoxyribonucleic acid, DNA, or ribonucleic acid, RNA) surrounded by a protein coat called the capsid. A capsid is built up of identical repeating protein subunits called capsomeres
here is absence of protoplasm in the xylem vessel. Thus mature xylem vessels are non-living. adaptation function
Absence of protoplasm reduces resistance to flow of water and dissolved mineral salts.
There is deposition of lignin, a tough substance, on its inner wall (cellulose cell wall). adaptation function
To prevent collapse as water is pulled up the plant by transpiration pull and to provide mechanical support to the plant.
Red blood cells (erythrocytes) function
Red blood cells (erythrocytes) contain a red pigment called haemoglobin that binds to oxygen, enabling them to function as oxygen transporters.
3 structural features of a red blood cell
- It has a biconcave disc shape (thinner central portion).
- It does not have a nucleus (enucleated).
- It is elastic.
RBC have biconcave disc shape (thinner central portion). function
The biconcave disc shape increases surface area to volume ratio for diffusion of oxygen into and out of the cell at a higher rate.
RBC does not have a nucleus (enucleated)
This enables it to contain more haemoglobin to maximise oxygen carrying capacity.
RBC is elastic.
This enables it to be flexible and squeeze through narrow capillaries.
SKELETAL MUSCLE CELLS function
Contraction of skeletal muscles, which is under voluntary control, enables the arms and legs to move.
1 skeletal muscle cell adaptation
The cell is elongated and cylindrical in shape, contains many nuclei, mitochondria and contractile proteins.
The cell is elongated and cylindrical in shape, contains many nuclei, mitochondria and contractile proteins.
Interaction between contractile proteins (actin and myosin) results in muscle contraction.
Many mitochondria ensure more energy is released in the form of ATP for muscle contraction.
does antibiotics or antibodies kill viruses
Antibiotics are not effective against viruses. They can only be destroyed by antibodies produced by the white blood cells.
what is the envelope for some viruses
A few viruses, such as the HIV and influenza viruses, have an **additional layer **around the capsid called the envelope which is derived from the cell surface membrane of the host cell. Some enveloped viruses are covered by spikes that project from the surface of the envelope and attach to host cells.
y arent viruses considered cells
they do not have cytoplasm
virus shapes
spherical shaped (influenza virus),
rod shaped (tobacco mosaic virus)
tadpole shaped (bacteriophage)
how do viruses reproduce
Viruses reproduce (replicate) only within living cells using biochemical systems of the cells, making new copies of themselves. A living cell which the virus attacks is called the host cell.
what happens to viruses outside the host cell
Outside the host cell, viruses do not feed, respire, excrete, grow or reproduce.
how are animal viruses taken into the cell
the whole virus may be taken into the host cell by endocytosis (for some animal viruses).
what happens once the virus is inside the host cell
Once inside the host cell, the animal virus is uncoated, i.e. its capsid is enzymatically removed, exposing its genetic material. Uncoating is not required for bacteriophages.
how doe the virus kill the cell
The host cell lyses, releasing new viral particles. Enveloped viruses do not lyse the host cell, instead they bud out from the cell surface membrane of the host cell. The host cell eventually dies from infection.
are bacteria living or non living cells
living cells
bacteria structures
cell surface membrane
cytoplasm
peptidoglycan cell wall,
chromosome
smaller rings of DNA known as plasmids
flagella
According to their shapes, bacteria may be classified into three general types:
Cocci (sing. coccus) – spherical-shaped bacteria
Bacilli (sing. bacillus) – rod-shaped bacteria (vibrio – comma shaped bacteria which is a variation of bacilli)
Spirilla (sing. spirillum) – spiral-shaped bacteria
how does bacteria reproduce
they reproduce asexually by binary fission
whats the only unicellular fungi
yeast
yeast structure
Most yeasts consist of separate, spherical cells. The thin cell wall encloses the cytoplasm, which contains a nucleus and a vacuole. In the cytoplasm are granules of
glycogen.
what is mycelium on a multicellular fungi
The body of a multicellular fungus like the bread mould consists of a mesh of finely branching threads collectively known as the mycelium
what is each mycelium composed of
Each mycelium is composed of long filaments called hyphae
what does the hyphal cell wall contain
The hyphal cell wall may contain cellulose or chitin, a complex carbohydrate, or both. Each hypha has cytoplasm and a central vacuole.
