Recent questions tagged cell-biology

Description : Can two normal individuals of the same species with sexual reproduction have identical genomes and identical karyotypes ? How the human karyotype is usually represented?

Last Answer : Except for clones (individuals created from nucleus transplantation, like the Dolly sheep) and monozygotic twins, it is very improbable the genomes of two individuals of the same species and generated by sexual ... normal karyotype is represented by the formula 44+XX for women and 44+XY for men.

Description : What is the difference between the concepts of karyotype and genome ?

Last Answer : Genome is the set of DNA molecules that characterizes each living being or each species. The concept then includes the specific nucleotide sequence of the DNA molecules of each individual or species. ... of each chromosome or pair of homologous. Cell Nucleus Review - Image Diversity: karyotype

Description : What are homologous chromosomes ?

Last Answer : Which are the human cells that do not have homologous chromosomes? Chromosomes contain genes (genetic information in the form of nucleotide sequences) that command the protein synthesis thus ... chromosomes are the gametes since during meiosis the homologous chromosomes are separated.

Description : What are the primary and the secondary constrictions of a chromosome ?

Last Answer : What is the other name given to the secondary constriction? Primary constriction is the narrower region of a condensed chromosome where the centromere, the structure that unites identical chromatids, is located. ... can be one or more in chromosome) is called nucleolus organizer region (NOR).

Description : How the chromosome region where the centromere is located is called ?

Last Answer : How are chromosomes classified in relation to the position of their centromere? The chromosome region where the centromere is located is called primary constriction. In microscopic view ... constriction the chromosomes are classified as telocentric, acrocentric, submetacentric or metacentric.

Description : What is the structure that maintains identical chromatids bound ?

Last Answer : The structure that maintains identical chromatids bound is the centromere. Cell Nucleus Review - Image Diversity: centromere

Description : How are the concepts of chromosome ?

Last Answer : chromatin and chromatids related? In which phase of the cell cycle does DNA duplicate? Chromatin is a set of filamentous DNA molecules dispersed in the karyoplasm forming euchromatin and heterochromatin ... chromosomes (and not only one). Cell Nucleus Review - Image Diversity: chromatids

Description : In the phase when the cell is not dividing ?

Last Answer : interphase) is there activity within the cell nucleus? In the interphase there is intense metabolic activity in the cell nucleus: DNA is duplicating, euchromatin is being transcript and RNA is produced.

Description : What is the relation between the concepts of chromatin and chromosome ?

Last Answer : Are euchromatin and heterochromatin part of chromosomes? Every filament of chromatin is a complete DNA molecule (a complete double helix), i.e., a complete chromosome. A DNA molecule may form ... thus both are part of chromosomes. Cell Nucleus Review - Image Diversity: chromosome structure

Description : What are heterochromatin and euchromatin ?

Last Answer : Chromatin is uncondensed nuclear DNA, the typical DNA morphology in interphase (the phase of the cell cycle in which the cells is not dividing itself). In this phase of the cell cycle ... inactive portions of the DNA molecule. Cell Nucleus Review - Image Diversity: heterochromatin euchromatin

Description : Do all eukaryotic cells have nucleus and only one nucleus ?

Last Answer : There are eukaryotic cells without nucleus and others with more than one nucleus. Osteoclasts, the cells responsible for resorption of the osseous matrix, for example, are multinucleate cells; ... cells. Cell Nucleus Review - Image Diversity: cell nucleus miltinucleate cells enucleated cells

Description : How are cells with delimited nucleus called ?

Last Answer : What are the main elements of the nucleus? Cells with delimited nucleus are called eukaryotic cells. Organisms composed of one or more eukaryotic cells are called eukaryotes. The mains elements of the ... the nucleolus, the karyolymph, or nucleoplasm, and the nuclear membrane (or karyotheca).

Description : What are some biological examples in which lysosomic enzymes play fundamental role ?

Last Answer : The remodelation of the osseous tissue, the function of acrosomes in sperm cells and the elimination of the tadpole tail are examples of biological processes in which lysosomic enzymes are key factors. The ... cell by its own mechanisms is called autolysis, a type of apoptosis (celll suicide).

Description : What is autophagic intracellular digestion ?

Last Answer : Why is this type of intracellular digestion intensified in an organism undergoing starvation? Autophagic intracellular digestion is the cellular internal digestion of waste and residual materials. In general ... obtain from its own constituent materials the nutrients necessary to stay alive.

Description : What is heterophagic intracellular digestion ?

Last Answer : How is this process accomplished? Heterophagic intracellular digestion is the breaking into smaller substances of external substances engulfed in the cell by pinocytosis or phagocytosis. Phagosomes or pinosomes fuse ... with the plasma membrane and liberates its waste in the exterior space.

Description : What is the main cell organelle involved in cell digestion ?

Last Answer : What are the properties of that organelle that enable it to the task? The organelles responsible for intracellular digestion are the lysosomes. Lysosomes are vesicles that contain digestive enzymes ... digested and then digestion takes place. Cell Digestion Review - Image Diversity: lysosomes

Description : What is intracellular digestion ?

Last Answer : Intracellular digestion, or cellular digestion, is the breaking in the interior of the cell of big molecules coming from outside or even from the own cell metabolism into smaller ... is classified into two types: heterophagic intracellular digestion and autophagic intracellular digestion.

Description : What is extracellular digestion ?

Last Answer : Extracellular digestion is that in which food breaking into utile molecules that can be internalized by the cell is done in the extracellular space, i.e., outside the cell. In extracellular digestion ... the external environment. Later the cell can benefit from these products of the digestion.

Description : What are some examples of secretory cells ?

Last Answer : Endocrine and exocrine pancreatic cells, thyroid and parathyroid endocrine cells, adenohypophysis, adrenal and pineal endocrine cells, the many types of gastric exocrine and endocrine cells, the mucous secretory cells ... of the ovaries and testicles, etc., are all examples of secretory cells.

Description : How do the rough endoplasmic reticulum and the Golgi apparatus act in the production and releasing of proteins ?

Last Answer : The rough endoplasmic reticulum has in its outer membrane numerous ribosomes, structures where translation of messenger RNA and protein synthesis occur. These proteins are stored in the rough endoplasmic reticulum ... exocytosis) in the right place and its content is liberated outside the cell.

Description : Which cell organelles are well-developed in secretory cells ?

Last Answer : In secretory cells, like the secretory cells of endocrine glands, organelles related to production, processing and exportation of substances are widely present and well-developed. These ... protein synthesis between the cytoplasm and the nucleus. Rough endoplasmic reticulum Golgi apparatus

Description : What is meant by cellular secretion ?

Last Answer : Cell secretion is the elimination to the exterior of substances produced by the cell (for example, hormones, mucous, sweat, etc.)

Description : What is cyclosis ?

Last Answer : Cyclosis is a type of internal cell movement in which an oriented flow of circulating material is created and maintained in the cytoplasm by the action of microfilaments. Cyclosis is more easily observed in plant cells. Cytoskeleton and Cell Movement - Image Diversity: cyclosis

Description : What are some examples of movement created by the contraction of sarcomeres of the muscle cells ?

Last Answer : The handling of a cup of coffee, the peristaltic movements of the bowels, the cardiac beats and even a smile are examples of movement created by contraction of the sarcomeres of the muscle cells. This contraction is a type of cell movement.

Description : How do the amoeboid movements occur ?

Last Answer : What are examples of beings and cells that use such movements for locomotion? Amoeboid movements are created by cytoplasmic movements and plasma membrane projections called pseudopods. Their formation ... in the inflammatory process. Cytoskeleton and Cell Movement - Image Diversity: pseudopods

Description : What are cilia and flagella ?

Last Answer : How do these structures acquire movement? What are some examples of ciliated and flagellated cells in humans? Cilia and flagella are structures found in some prokaryotes as well in some eukaryotic ... the ovule. Cytoskeleton and Cell Movement - Image Diversity: ciliated cell flagellate cell

Description : What are cell movements ?

Last Answer : How are these movements created? Cell movements are movements performed by cell structures, like the movements of cilia and flagella, the pseudopod movements (in amoeba, macrophages, etc. ... action, by differences of viscosity among cytoplasmic regions and by intracellular contraction systems.

Description : which substance are microtubules made ?

Last Answer : In which structures and cellular processes do microtubules participate? Microtubules are made of consecutive dimers of the protein tubulin (each dimer has an alpha and a beta tubulin associated) ... also form the centrioles. Cytoskeleton and Cell Movement - Image Diversity: microtubules tubulin

Description : What is cytoskeleton ?

Last Answer : What are its main constituents in animal cells? Cytoskeleton is the cytoplasmic structure that supports the cell, keeps its shape and fixates and moves the cell organelles. It is made of an ... intermediate filaments. Cell Skeleton and Cell Movement - Image Diversity: the "cell skeleton"

Description : Why are salt and sugar used in the production of dried meat and dried fruits ?

Last Answer : Substances that maintain highly hypertonic environment, like sugar and salt, are used in the production of dried meat, fish or fruits (for example, cod) because the material to be conserved is then ... the growth of populations of decomposer beings (since these beings also lose water and die).

Description : What is deplasmolysis of plant cells ?

Last Answer : The plant cell when placed under hypertonic medium loses a great amount of water and its cell membrane detaches from the cell wall. In that situation the cell is called plasmolysed cell. When ... medium it absorbs water and becomes a turgid cell. This phenomenon is called deplasmolysis.

Description : Since DPD ?

Last Answer : SF – TP and TP is negative (< 0) its formula becomes DPD = SF + |TP|.

Description : What is the formula of the DPD for withered ?

Last Answer : shrank) plant cells? How is that situation possible? Withered plant cells are those that shrank due to loss of water by evaporation without enough replacement. In this situation the cell membrane retracts ... The cell wall moreover expands in length to stimulate the entrance of water making TP <

Description : The cell that expanded itself to this point is called turgid cell ?

Last Answer : Cell Membrane Review - Image Diversity: plasmolysed cell flaccid cell turgid cell

Description : What are the values of DPD for plant cells under hypertonic ?

Last Answer : isotonic and hypotonic media? In plant cells under hypertonic medium there is loss of water for the exterior, SF > 0 (the vacuolar pressure is high because it is concentrated) and TP = 0 (there ... (since the osmotic pressure is totally compensated by the distension of the cell wall) and DPD =

Description : What does the formula DPD ?

Last Answer : SF - TP mean? DPD is the abbreviation of diffusion pressure deficit, SF (suction force) is the vacuolar osmotic pressure and TP is the turgor pressure. The difference between SF and TP determines whether water tends ... osmosis. If TP > SF, DPD < 0 and water cannot enter the cell by osmosis.

Description : What is the wall resistance of plant cells ?

Last Answer : Does this resistance facilitate or make it difficult the entrance of water in the cell? Wall resistance, or turgor pressure (TP), is the pressure made by the distension of the plant cell wall in ... it acts forcing the exiting of water and compensating the entrance of the solvent by osmosis.

Description : What is meant by suction force of the plant cell ?

Last Answer : Does the suction force facilitate or make difficult the entrance of water in the cell? The suction force (SF) is the osmotic pressure of the plant cell vacuole, i.e., of the vacuolar internal ... vacuole the cytosol becomes hypertonic in relation to the exterior and more water enters the cell.

Description : How does the plant cell wall react when it is placed under hypotonic medium ?

Last Answer : The plant cell wall (the covering of the cell external to the cell membrane) is made of cellulose, a polymer of glucose. When the cell is put under hypotonic medium it absorbs too ... compensate the osmotic pressure thus forbiding excessive increase of the cellular volume and the cell lysis.

Description : What are the two main types of endocytosis ?

Last Answer : Endocytosis is the entrance of materia in the cell engulfed by portions of the cell membrane. Endocytosis can be classified as pinocytosis or phagocytosis. In pinocytosis small particles on ... receiving the name phagosome. Cell Membrane Review - Image Diversity: pynocitosis phagocytosis

Description : What is mass transportation across the cell membrane ?

Last Answer : Mass transportation is the entrance or the exiting of substances in or from the cell engulfed by portions of membrane. The fusion of internal substance-containing membranous vesicles with the cell ... cell after they have been engulfed by projections of the membrane is called endocytosis.

Description : How does the sodium-potassium pump present in the cell membrane work ?

Last Answer : What is the importance of this protein for the cell? The sodium-potassium pump is the transport protein that maintains the concentration gradient of these ions between the intra and the ... maintain the cellular metabolism. Cell Membrane Review - Image Diversity: sodium-potassium pump

Description : Which are the molecules that make possible active transport through membranes ?

Last Answer : Active transport is made by specific membrane proteins. These proteins are called “pumps” because they “pump” the moving substance through the membrane using energy from ATP molecules.

Description : What do facilitated diffusion and active transport have in common ?

Last Answer : What are the differences between them? Facilitated diffusion can be confused with active transport because in both processes there is participation of membrane proteins. In active transport however the ... it does not require energy. Cell Membrane Review - Image Diversity: active transport

Description : What are some examples of biological activities in which osmosis plays important role ?

Last Answer : Hemolysis (destruction of red blood cells) by entrance of water, the hydric regulation in plants and the entrance of water in the xylem of vascular plants are all examples of biological phenomena caused by ... of water in plant roots since root cells are hypertonic in comparison to the soil.

Description : How does facilitated diffusion present similarities with enzymatic chemical reactions ?

Last Answer : One of the main examples of facilitated transport is the entrance of glucose from the blood into cells. Glucose from blood binds to specific permeases (hexose-transporting permeases) present in the ... job is concluded the permease is not consumed and can perform successive other transports.

Description : Without saturation of transport proteins and under same concentration gradient how can the speed of simple diffusion be compared to the speed of facilitated diffusion ?

Last Answer : The action of facilitator proteins in facilitated diffusion makes this type of diffusion faster than simple diffusion under equal concentration gradients of the moved substance.

Description : How does the intensity of facilitated diffusion vary in relation to the concentration of the moved substance ?

Last Answer : What is the limiting factor? Likewise simple diffusion facilitated diffusion is more intense when the concentration gradient of the substance increases and less intense when the gradient lessens. In ... which the maximum transport capacity of the substance across the membrane is achieved.

Description : How does the intensity of simple diffusion vary in relation to the concentration gradient of the moved substance ?

Last Answer : The higher the concentration gradient of a substance the more intense its simple diffusion will be. If the concentration gradient diminishes the intensity of simple diffusion diminishes too.

Description : What is the difference between simple and facilitated diffusion ?

Last Answer : Facilitated by which type of molecule does the term facilitated mean? Simple diffusion is the direct passage of substances across the membrane in favor of their concentration gradient. In ... their passage through the membrane. Cell Membrane Review - Image Diversity: facilitated diffusion