Cell structure (basic) Flashcards
Nucleus
contains hereditary material (like DNA-carrying the information for protein synthesis). DNA is bound up with a histone protein to form chromatin.Contains one or more nucleoli-where ribosome submits, ribosomal RNA and transfer RNA are manufactured. Surrounded by double membrane, crossed by a number of nuclear pores. Usually one nucleus per cell BUT may be many in very large cells like skeletal muscles
what does DNA carry the information for
protein synthesis
what is DNA bound up by
histone protein to form chromatin
what three things are manufactured in the nucleoli>
ribosome subunits: ribosomal RNA and transfer RNA are manufactured
what type of cells may have many nucleus’
a striated (skeletal) muscle
Mitochondrion-pl. mitochondria
Site of aerobic respiration. Highly folded inner membrane which supports the proteins of the electron transport chain responsible for the synthesis of ATP by oxidative phosphorylation. These organelles are abundant in cells which are physically (skeletal muscle) and metabolically (hepatocytes) active.
what mainly happens here
it is the site of aerobic respiration
what do mitochondria have
a tightly folded inner membrane
why does it have a tightly folded inner membrane
to support the proteins of the electron transport chain responsible for the synthesis of ATP by oxidative phosphorylation
where are these organelles most abundant
in cells which are physically (skeletal muscle) and metabolically (hepatocytes) active
cytoplasm
mainly water-with solutes including glucose, proteins and ions. Supported by the CYTOSKELETON, made up of microtubles and microfilaments
what is cytoplasm mainly made of
water
what is dissolved in the water
glucose, proteins and ions
what is cytoplasm supported by
CYTOSKELETON-made up of microtubles and microfilaments
Free ribosomes
site of protein synthesis, mostly for proteins destined for intracellular use. there may be 50 000 or more in a typical eukaryote cell
microvilli
extensions of plasma membrane (cell membrane), increase the surface area of the cell. Commonly abundant in cells with a high absorptive capacity, such as epithelial cells of the small intestine or cells of the first coiled tubule of the nephron. Brush border of the cell
where are cells with microvilli most coomon
in cells with high absorptive capacity, such as epithelial cells of the small intestine or cells of the first coiled tubule of the nephron
endocytic vesicle
may contain molecules or structures too large to cross the membrane by active transport or diffusion
microfilaments
threads of the protein actin. Found in bundles beneath the call surface and play roles in endo- and exocytosis and possibly cell movement
Centrioles
a pair of structures, held at right angles to one another, act as organisers of the nuclear spindle in the preparation for the separation of chromosomes or chromatids during nuclear division
secretory vesicle
undergoing exocytosis. may be carrying a synthetic product of the cell (such as a protein packaged at the Golgi body) or the product of degradation by lysosomes. Abundant in cells with a high synthetic activity, such as cells of isles of langerhans
process in which secretory vesicle is going through
EXOCYTOSIS
what packages the synthetic product of the cell
Golgi body
smooth endoplasmic reticulum
a series of flattened sacs and sheets that are the site of synthesis of steroids and lipids
rough endoplasmic reticulum
so-called because of the many ribosomes attached to its surface. This intracellular system aids cells compartmentalisation and transports proteins synthesised at the ribosomes towards the Golgi body for secretory packing
Golgi apparatus
consists of a stack of sacs called CISTERNAE. It modifies a number of cell products delivered to it, often enclosing them in vesicles to be secreted. Such proteins include TRYPSINOGEN, INSULIN AND MUCIN. Also involved in lipid modification in cells of the ileum, and plays a part in the formation of lysosomes.
Plasmalemma (cell membrane)
surface of the cell and represent sits contact with the environment. It is differentially permeable and regulates movement of solutes between the cell and its environment.
Place in the correct order to show the passage of an amino acid from the cytoplasm a until it is secreted from the cell as a protein
cytoplasm->?->?->?-> protein
A group of scientists homogenised tissue before carrying out cell fractionation to isolate an organelle Explain why the scientistshomogenised the tissue?filtered the resulting suspension?kept the suspension ice cold during the process?used isotonic solution during the process?(2)
1.Breaks open cells / disrupts cell membrane / releases cell contents / releases organelles / break up cells2.Removes (cell) debris / complete cells / tissue3.Reduces / prevents enzyme activity4. a.Prevents osmosis / no (net) movement of water / water does not enter organelle / water does not leave organelle;4, b. So organelle / named organelle is not damaged / does not burst / does not shrivel;
Name two structures present in an epithelial cell from the small intestine that are not present in a cholera bacterium
Nucleus / nuclear envelope / nuclear membrane / nucleolus;Mitochondrion;(Smooth / rough) ER;Lysosome;Microvillus / brush border;Golgi;Linear / non-circular DNA / chromosome; 80S / denser / heavier / larger ribosomes
Give one advantage of using a TEM rather than a SEM.
Higher resolution / higher (maximum) magnification / higher detail (of image);ORAllows internal details / structures within (cells) to be seen / cross section to be taken
Give one advantage of using a SEM rather than a TEM.
Thin sections do not need to be prepared / shows surface of specimen / can have 3-D images
The epithelial cells that line the small intestine are adapted for the absorption of glucose. Explain how.
- Microvilli2. Large/increased surface area3. Many mitochondria4. (Mitochondria/respiration) produce ATP / release or provide energy (for active transport)5. Carrier proteins for active transport6. Channel / carrier proteins for facilitated diffusion7. Co-transport of sodium (ions) and glucose or symport / carrier protein for sodium (ions) and glucose8. Membrane-bound enzymes digest disaccharides / produce glucose
The scientists used a transmission electron microscope to study the structure of an amoeba. Explain why
- High/ better resolution2. Shorter wavelength3. To see internal structures/ organelles/named organelles
What is the function of the mitochondrion?
(Aerobic) respiration
Microfold cells are found in the epithelium of the small intestine. Unlike other epithelial cells in the small intestine, microfold cells do not have adaptations for the absorption of food.Microfold cells help to protect against pathogens that enter the intestine. They have receptor proteins on their cell-surface membranes that bind to antigens on the surface of pathogens. The microfold cells take up the antigens and transport them to cells of the immune system. Antibodies are then produced which give protection against the pathogen.Scientists believe that it may be possible to develop vaccines that make use of microfold cells. These vaccines could be swallowed in tablet form. Use information from the passage and your own knowledge to answer the following questions.Microfold cells do not have adaptations for the absorption of food . A. Give two adaptations that other epithelial cells have for the absorption of foodB. Microfold cells have receptor proteins on their cell-surface membranes that bind to antigens . What is an antigen?
A. 1. Microvilli2. Carrier proteins/co-transport proteins/membrane-bound enzymes3. Many mitochondriaB.Substance that causes an immune response/production of antibodies
Microfold cells take up the antigens and transport them to cells of the immune system . Antigens are not able to pass through the cell-surface membranes of other epithelial cells. Suggest two reasons why
- Not lipid soluble2. Too large (to diffuse through the membrane)3. Antigens do not have the complementary shape/cannot bind to receptor/channel/carrier proteins (in membranes of other epithelial cells)
