Eukaryotic Cell Structure and Function

Plant and animal cells are both eukaryotic cells, so they have several features in common, such as the presence of a nucleus with nuclear membrane and membrane-bounded organelles. 80S ribosomes are present in both the type of cell.

Eukaryotic cells contain a membrane-bound nucleus. The nuclear membrane that surrounds nucleus in eukaryotic cells gives the defined structure to the nucleus which consists genetic material and thus eukaryotic nucleus is called as well developed nucleus.

Mitochondria are organelles in cells of eukaryotes. They are double-membraned and the inner membrane forms numerous folds called cristae which extend into the matrix.

Eukaryotic cells contain a well organized, membrane-bound nucleus and organelles (mitochondria, lysosomes, Golgi apparatus) and not found in prokaryotes like bacteria, cyanobacteria. Eukaryotic cells are more complex than prokaryotic cells and are found in a great many different forms. Thus, the correct answer is option A.

Eukaryotes are the organisms which have membrane-bound cell organelles as well as membrane-bound nucleus. All the kingdoms except kingdom monera possess eukaryotes.

Cell organelles like mitochondria, nucleus, Golgi apparatus etc are components of an eukaryotic cell

The prokaryotic cell is the cell devoid of nuclear membrane and membrane-bound organelles whereas eukaryotic cell has membrane bound nucleus and organelles. Cyanobacteria are the prokaryotic microscopic organism (kingdom Monera) while algae, fungi, mosses, fern and spermatophytes (angiosperms and gymnosperms) are eukaryotes.
So, the correct answer is option A.

Prokaryotes are the organism whose cell do not possess membrane-bound nucleus and organelles except ribosome. Instead of organelles, all the function is performed by the cytoplasm and cell membrane. Whereas eukaryotes are the organism whose cell possess membrane-bound organelle and nucleus. Prokaryotic cell possesses single circular chromosome whereas eukaryotic cell possesses more than one chromosomes. Thus, the correct answer is option D.

• The eukaryotic cell contains double membrane-bound organelles like mitochondria, Golgi body, lysosomes, etc.
  
• Prochromosomes are not present in the eukaryotic cell rather its DNA is linear and condensed to form a structure called chromosomes.
  
• True sap vacuoles are present in plant cells they serve as storage of material.
  
• The eukaryotic cell contains 80S ribosomes which are made up of two units first one is a small unit (40S) and the second one is a large unit (60S).
  

In prokaryotes, the circular chromosomes are located in nucleoid which is present in the cytoplasm. In eukaryotes, the chromosome is stored inside the nucleus. Each eukaryotic chromosome is composed of DNA coiled and condensed around nuclear proteins called histones.

It is the nuclear membrane that encloses and protects the chromosome. It is present only in the Eukaryotic cells.

The cells of animals, plants and fungi have a true nucleus i.e. a nucleus where the nuclear membrane is covering the chromosomes. Such cells with a true nucleus are called the Eukaryotic cells.

The various cell organelles that can be seen in the eukaryotic cell cytoplasm include the nucleus, cell membrane, cytoplasm, endoplasmic reticulum, Golgi bodies, mitochondria, lysosomes, vacuoles and the ribosomes. The nucleoid is the naked chromosome which is found in the prokaryotic cells like bacteria and the mesosome is also found in the prokaryotic cells where it plays an important role in the respiration. Pili are hair-like structures that help the bacteria to adhere to the surfaces. So, the correct answer is 'The mitochondria, nucleus, cytoplasm, cell membrane, Golgi bodies and endoplasmic reticulum'.

The Eukaryotic cells, in addition to the nucleus, have many membrane-bound organelles like the mitochondria, endoplasmic reticulum, Golgi bodies etc. Such membrane-bound organelles are absent in the Prokaryotic cells.

Mitochondria is called as "power house of the cell". But kitchen of the cell is chloroplast, which is present only in plant cells. Chloroplast is referred as 'Kitchen of the cell' because in it, the food is being synthesized with the help of carbondioxide, sunlight and water.

The eukaryotic cells are the advance cells that  have a well-defined nucleus that is surrounded by a double-layered nuclear membrane. Within the nuclear membrane, the genetic material is present on the chromosomes. The genetic material is double-stranded DNA that is bound with positively charged histone proteins. The nucleus also has its own nucleoplasm that serves as the base for the nuclear activities like DNA replication and RNA formation. 

Both the sap vacuoles and periplasmic membrane of bacteria contains the hydrolytic enzyme for their digestive purposes.

The ribosome is found in both prokaryotes (70s) and eukaryote (80s). The ribosome is a complex molecule made of ribosomal RNA molecules and proteins that form a factory for protein synthesis in the cell.

The 70S ribosome is found in prokaryotic organisms and mesosome are invaginations of cell membrane so they do not contain any ribosome.

A cell requires several mineral elements for various structural and metabolic roles. The calcium is the most abundant element in eukaryotic cells. It is required for integrity of plant cell wall. In animals, calcium is important for membrane permeability, muscle activity, blood clotting and its role as second messenger. 

Prokaryotes are the organism that does not possess a well-defined nucleus. Nucleoid is a region in the prokaryotic cell where its most of the genetic material resides. It is not a well-defined membrane-bound region. 
Eukaryotic cells possess a well-organized nucleus (like eukaryotes) but its nucleus divides through amitosis (like prokaryotes). Dinoflagellates cells are mesokaryotic cells.  
The nucleus is bound to double membrane in the eukaryotic cell in which most of the genetic material is present and undergoes mitotic division.
So, the correct answer is option A.

During post-transcriptional processing in eukaryotes, primary transcripts undergo splicing to remove non-coding introns and join coding exons together. Therefore, the mature mRNA contains exons but lacks introns.

Eukaryotic cells are the cells which contain well developed, membrane-bounded nucleus and organelles such as mitochondria and the Golgi apparatus. In addition, plants and algae contain chloroplasts. Any organism, whose cells contain a nucleus and other organelles enclosed within membranes belong to the taxon Eukarya or Eukaryota. Thus, the correct answer is option C.

Statement (iv) is incorrect because eukaryotic cells possess a well-defined nucleus enclosed by a nuclear envelope. Statements (i), (ii), and (iii) are correct characteristics of eukaryotic cells.

Histones are highly alkaline proteins found in eukaryotic cell nuclei that package and order the DNA into structural units called nucleosomes. Their basic nature is due to a high proportion of basic amino acids like lysine and arginine.

Any organism composed of eukaryotic cells is also considered a eukaryotic organism.

Eukaryotes are organisms whose cells have well-developed membrane bound nucleus and organelles such as mitochondria, Golgi body, ER etc. Animals, plants, fungi and protists are eukaryotes.

Pseudopodia, are the locomotory organs, which are mainly present in the prokaryotic cell or the unicellular protist. These are cytoplasm filled temporary projections. These are also used for the process such as phagocytosis. It is also used in major mechanism to remove pathogens and cell debris e.g.,

Amoeba.

Plant and animal cells are both eukaryotic cells so they have several features in common, such as the presence of a cell membrane and cell organelles like the nucleus, mitochondria, and endoplasmic reticulum.

The odd one out of the following options is the gamete. The chromosome, nucleus and the gene are the parts of the DNA. The chromosomes are the condensed form of the DNA and histones. The nucleus is the site where the DNA is present and the gene is the segment of DNA which encodes for the proteins. The gamete is the haploid cell which is produced by the meiotic division of the germ cells. 

• Prokaryotes are the organisms, that lack membrane-bound organelles while eukaryotes have these organelles. 
• ER is a eukaryotic organelle with a network of tubules, vesicles, and cisternae within the cells.
• Ribosomes are the nonmembrane bound organelles and are found in both prokaryotes and eukaryotes. 
• DNA is the genetic material present in both prokaryotes and eukaryotes.
  
  Hence, the correct answer is option E.

The chromosomes are composed of DNA and histone proteins. The ribosomes are composed of RNA and proteins. Both the structures contain the nucleic acid as well as proteins in them. The chromosomes are found in the nucleus but the ribosomes are present in the cytoplasm and on the surface of RER. 

• The plant and animal cells are eukaryotic and contain well developed cellular organelles. 
• The cell membrane, cytoplasm, chromosomes, and mitochondria are the structures that are present in both the plant and the animal cells. 
• The cell wall and chloroplast are present only in the plant cell. 
  
  

• Dougherty in the year 1957 suggested that there exist fundamental differences between prokaryotic and eukaryotic cells
  
• A eukaryotic cell consists of membrane-bound organelles and nucleus with its envelope-pore membrane complex whereas, they are absent in a prokaryotic cell.
• So, the correct answer is 'Dougherty'.

• Ribosomes are known as protein factories because they are the main site of protein synthesis. 
  
• It is made up of two subunits-
• Large subunits- join amino acids to form a polypeptide chain.
• Small subunits- reads RNA.
• In a eukaryotic cell, the ribosome present is an 80S type and the cellular organelles (mitochondria and chloroplasts) have 70S type 
• It is made up of two subunits- a larger subunit 60S and a smaller subunit 40S.
• So, the correct answer is 'Both B and C'.

• Prokaryotes differ from eukaryotes in the absence of histones.
• A prokaryotic cell does not have complex histone proteins as present in the eukaryotic cell.
• They instead have smaller, less complex, basic proteins called histone-like proteins.
• HU is a folding protein which is abundantly found in the nucleoid.
• So, the correct answer is 'Histones'.

• Glyoxysomes are a type of peroxisomes found in plants and few filamentous fungi.
  
• They are particularly found in fat storage tissues of germinating seeds (peanuts, soybeans etc.) in plants.
• They contain enzymes (citrate synthase, isocitrate lyase and malate synthase etc.) which are responsible for beta-oxidation of fatty acids,
• It helps in fatty acid oxidation, glyoxylate cycle and gluconeogenesis.
• So, the correct answer is 'Fatty seeds'.

• Structurally, plant and animal cells are very similar because they are both eukaryotic cells.
  
• The common characteristics in plant and animal cells are They both contain membrane-bound organelles such as the nucleus, mitochondria, endoplasmic reticulum, golgi apparatus, lysosomes, and peroxisomes. 
  
• The mitochondrion is a double-membrane-bound organelle found in most eukaryotic organisms i.e both plant and animals.
  
• Hence mitochondria is common in plant and animal cells.
• So, the correct answer is 'Mitochondria'.

• Cytoribosomes of eucaryotes is different from those of bacterial cells in having a larger size.
  
• Ribosomes are known as protein factories because they are the main site of protein synthesis. 
  
• It is made up of two subunits-
• Large subunits- join amino acids to form a polypeptide chain.
• Small subunits- reads RNA.
• In a prokaryotic cell, the ribosome is 70S type whereas, in a eukaryotic cell it is an 80S type.
• So, the correct answer is 'Larger size (80 S type)'.

• The endoplasmic reticulum is a membrane-bound organelle within the cytoplasm of a cell which is responsible for modifying and packaging of proteins (rough) and also involved in lipid and steroid synthesis (smooth).
• The eukaryotic cell with few endoplasmic reticula is considered to be embryonic cells in the early stages of development, egg cells or resting cells where the above function is not actively performed as in a well-developed cell.
• So, the correct answer is 'All the above'.

• The nucleus is a double membrane-enclosed organelle which contains the genetic information and is known as the controlling centre of the cell.
• The mitochondria is a double-membraned cell organelle, known as the powerhouse of the cell which is present in all eukaryotic cells.
• Plastids are a pigment containing double membrane-bound organelle which is the site of manufacture and storage of chemical compounds.
• So, the correct answer is 'All of the above'.

Euglenoids are unicellular flagellate protists. They are without the cell wall. The body is covered by thin and flexible pellicle which is a protein-rich layer. The pellicle has oblique but parallel stripes called myonemes. The pellicle is composed of fibrous elastic protein, the small amount of lipid and carbohydrates and maintains a definite shape. It is flexible enough to permit temporary changes in the body shape.

Paramecium is a tiny unicellular protozoan which shows the holozoic mode of nutrition. It shows the presence of a large number of cilia on whole body surface. It engulfs food using cilia. During unfavourable condition, it forms cysts. Under the favourable condition, the cyst releases many organisms. It contains contractile vacuole for osmoregulation. Excess water is thrown out through contractile vacuole outside. It uses trichocysts for capturing prey.

The defining characteristic of a eukaryotic cell compared to a prokaryotic cell is the presence of a true, membrane-bound nucleus.

Vacuoles are non-cytoplasmic areas present inside the cytoplasm which are separated from the latter by specific membranes. Vacuoles are believed to be formed by expansion and pinching off from ER. Tonoplast is the covering of the vacuole. It is a selectively permeable membrane. It separates the vacuoles from the cytoplasm.

Eukaryotes
are the organisms which have membrane bound cell organelles as well as membrane
bound nucleus. All the kingdoms except kingdom monera are eukaryotes. Monera is
a kingdom of prokaryotes. It includes the most primitive forms of life which
developed from an early stock called progenote. Being the earliest forms of
life, monerans are adapted to all types of habitats. Population wise they are
the most numerous of all organisms. They are found everywhere, wherever organic
matter can be present or can be supported. They have very little morphological
differentiation. Archaebacteria and eubacteria are the two major groups of
monera.

A eukaryote is the organism with complex features, i.e, it is apart from the prokaryotic cell it has membrane-bound organelles, especially the nucleus, which contains the genetic material enclosed by the nuclear membrane. A eukaryotic cell has a plasma membrane, cytoplasm, and ribosomes (including the endoplasmic reticulum, Golgi apparatus, chloroplasts, and mitochondria). 

• Cuticle can be defined as a protective film which covers the epidermis of leaves, young shoots and aerial parts of the plants.
• It is mainly made up of lipids and hydrocarbon polymers that is impregnated with wax which is synthesized by the epidermal cells.
• So, the correct answer is 'Plant cell'.

Statement 1 is false (no eukaryotes fix nitrogen). Statements 2, 3, and 4 are correct. Since only one statement is false, the answer 'One' is correct.

According to the endosymbiotic theory, two major organelles in eukaryotic cells are considered to have evolved from independent prokaryotic organisms, namely mitochondria and chloroplasts. Both contain their own circular DNA and prokaryotic-like ribosomes.

Eukaryotic cells are multicellular cells. They have a well organized nucleus enclosed within nuclear membrane. They have cell organelles like mitochondria, chloroplast, lysosomes, peroxisomes, Golgi bodies, etc. Prokaryotic cells are unicellular cells. They do not have nuclear membrane. Blue green algae are prokaryotic cells as they do not have  membrane bound organelles and nucleus.

Algae, bryophytes, pteridophytes, gymnosperms, and angiosperms are all members of the domain Eukaryota.

A mature erythrocyte has all the characters of a eukaryotic cell except the fact that they lack nucleus & other organelles because they shed other organelles  during maturation.

Informosomes are messenger RNA molecules combined with protein, forming ribonucleoprotein complexes that remain stable and untranslated in the cytoplasm for extended periods. They were first discovered by Spirin in embryonic development.

Cycloheximide inhibits protein synthesis in eukaryotes by blocking the elongation phase during translation, making option A correct. Option D has a typo (erythromycin, not 'erythyromycin'). Formylated mRNA is for prokaryotic initiation, and single mRNA producing multiple products (polycistronic) is prokaryotic.

Sap vacuoles are fluid filled vacuoles or vesicles which are separated from the cytoplasm by a selectively permeable membrane called tonoplast. A number of small sap vacuoles occur in animal cells and young plant cells. In mature plant cells, small vacuoles fuse to form a single large central vacuole. The fluid present in the sap vacuoles is often called cell sap or vacuolar sap. It contains minerals, sugars, oxygen, carbon dioxide, soluble pigments and organic acids. The pigments include anthocyanins (red, purple, blue) and anthoxanthins (ivory to deep yellow). So, the correct answer is 'Vacuole'.

Eukaryotic gene expression is more complex because it must generate and maintain differentiated cell types (neurons vs. muscle vs. skin), each with specialized gene expression profiles. Option A correctly states this. The other options describe structural features, not regulatory complexity.

A plant cell has rigid wall on the outside. It has plastids like chloroplasts, leukoplasts and chromoplasts and centrally located large vacuole. All of these are absent in an animal cell.

Prokaryotes and many eukaryotes contain a structure outside the cell membrane called the cell wall. With only a few exceptions all prokaryotes have thick, rigid cell walls that give them their shape. Among eukaryotes, some protists and all fungi and plants have cell wall.

The prokaryotic cells lack the nucleus and were the first and simplest life forms and were originated 3.8 billion years ago. But the eukaryotic cells originated 1.5 billion years ago were complex than prokaryotes as they contained the nucleus and the most complex forms called multicellular organisms originated about 600 million years ago. So, the correct option is "origin of eukaryotic cells 1.5 billion years ago".

Following characteristics of Archaebacteria that they share with eukaryotes:

• Inside the cell wall, if present, do not contain muramic acid (therefore, no peptidoglycan). 
• A eukaryotic cell has 80S ribosomes present in the cytoplasm. 
• Membrane-bound organelles are present, like, mitochondria, ER, Golgi apparatus, chloroplasts, etc. 
• Mitochondria are semi-autonomous organelles, which are double membrane-bound and have their own ribosomes (70S) and DNA (circular).
  
• So, (A) statement is not true for the eukaryotic cells.

Gene silencing by dsRNA makes use of the naturally occurring cell machinery that is involved in the processing of miRNA in eukaryotic cells. It does not provide any defense mechanism. So the correct answer is ' RNAi silencing takes place in all eukaryotic cells for cellular defense'.

Carbon dioxide, has two atoms of oxygen and one atom of carbon, making it the smallest one among the given options. Phospholipids are amphipathic molecules, having phosphate head group and fatty acid tails. DNA polymerase is polypeptide enzyme while ribosomes are the assemblage of rRNA and proteins. 
The correct answer is option A.

• Cytoplasm is a semifluid matrix present within a cell surrounding the nucleus (i.e without the nucleoplasm) which is enclosed by a cell membrane.
• They are the nonnuclear content of protoplasm in which all of the cell organelles are embedded.
  
• A cytoplasmic membrane or cell membrane is a phospholipid bilayer that separates the cell from the external environment.
  
• Protoplasm is the living substance of a cell that is enclosed by a plasma membrane and includes the nucleoplasm.
• So, the correct answer is 'Cytoplasm'.

The characteristics of a eukaryotic plant cell are

Organelles are small, specialised structures which perform a specific function within the cell. Organelles are enclosed by their own membrane.  They are found in eukaryotic cells. Their function is from generating energy to the cell to controlling of cell's growth and reproduction.

Centrifugation of cells is a sedimentation process used to separate certain organelles for analysis of specific parts of cells. a sample of tissue is lysed to break the cell membranes and mix up the contents of the cell. However, while the procedures may break many of the membranes of the cell including the plasma membrane and endoplasmic reticulum, it leaves certain  organelles such as mitochondria, nuclei, Golgi apparatus, peroxisomes and lysosomes intact in a homogeneous extract. During the process, particles of different densities or size sediment at different rates. The largest and most dense particle sediments first followed by less dense and smaller particles. Hence the cellular organelle concentrated on the top of the centrifuged mixture will be the mitochondria due to its less density and small size. Thus, the correct answer is option C.

• A mesokaryotic (meso= in between, karyon= nucleus) cell shows intermediate resemblance to both eukaryotic and prokaryotic cell.
  
• It contains well-developed nucleus but it undergoes cell division by amitosis (because the mitotic spindle is not formed).
• This condition in a cell was first distinguished by Dodge in the year 1966.
• So, the correct answer is 'Dodge'.

In eukaryotic cells, the nucleus is bound by a double membrane or nuclear envelope. It possesses openings at certain intervals called as 'nuclear pore'. Nuclear pores are large protein complexes regulates the exchange of material between nucleus and cytoplasm, i.e., nucleo-cytoplasmic exchange of materials. 

The 9+2 microtubule arrangement (9 outer doublets + 2 central singlet microtubules) is characteristic of eukaryotic flagella and cilia. Bacterial flagella use a different structure (filament + hook + basal body), and fimbriae are protein filaments without this arrangement.