Cells and Life - GED Science

Mitochondria are the only organelle defined correctly. The main processes of cell respiration, namely the electron transport chain, occur in the mitochondria to produce energy in the form of ATP. Because of this, mitochondria are known as the "powerhouses" of the cell.

Ribosomes are responsible for transcribing RNA and creating new proteins. The Golgi body packages proteins into vesicles that can be transported out of the cell. Lysosomes contain enzymes that can digest old or damaged proteins. The smooth endoplasmic reticulum is responsible for synthesizing lipids and for degrading toxins, such as alcohol.

Nonmembranous organelles are always in contact with cytosol.

Membranous organelles are surrounded by membranes that isolate their contents from the cytosol.

Ribosomes are freely scattered in the cytoplasm and thus are nonmembranous organelles.

One of the functions of the endoplasmic reticulum is to secrete proteins.

It's other functions include: synthesis of secretory products, intracellular storage, transport, and calcium ion storage.

Mitochondria are organelles that have an unusual double membrane. An out membrane surround the entire organelle, and a second, inner membrane contains numerous folds, called cristae. Cristae increase the surface area exposes to the matrix of mitochondria.

The plasmalemma (plasma membrane) has a complex structure composed of phospholipids, proteins, glycolipids, and cholesterol. The phospholipids form two distinct layers that don't allow dissolved ions and water-soluble compounds to cross the plasmalemma. This makes the plasmalemma effective in isolating the cytoplasm from the surrounding fluid environment.

Mitochondia produce energy (ATP) required by the cell, if a cell has large amounts of mitochondria this implies the cell has a high energy requirement.

Only lysosomes remove damages organelles or pathogens. Peroxisomes degrade fats and other organic compounds as well as neutralize toxic compounds.

The ER has four major functions: Synthesis, storage, transport, and detoxification.

Synthesis - ER membrane contains enzymes that manufacture carbohydrates, steroids, and lipids.

Storage - ER holds synthesized molecules absorbed from the cytosol.

Transport - Substances travel from place to place within the cell inside the ER.

Detoxification - Cellular toxins are absorbed by ER and neutralized by enzymes in ER membrane.

Plant cells have chloroplasts, which is the organelle where photosynthesis takes place, but animal cells do not. Plant cells contain both a cell membrane and a cell wall, but animal cells only have a cell membrane. Plant cells have a large vacuole and animal cells have small vacuoles. Animal cells have centrioles, but plant cells do not. All other organelles are found in both plant and animal cells.

Ribosomes manufacture proteins, the smooth endoplasmic reticulum transports materials within the cells, the rough endoplasmic reticulum transports ribosomes which are made in the nucleolus to other parts of the cell, and the cytoplasm is the living material that cushions the cell and allows chemical reactions to occur.

There are two fundamental sections of the cell cycle: mitosis and interphase. The M phase denotes mitosis, during which the cell divides. Interphase is composed of several subsections during which the cell grows, organelles replicate, and the cell prepares for division.

Interphase can be divided into the subsections G1, S, and G2. While G1 and G2 are dedicated to the growth of the cell and organelle replication, the S phase is when cellular DNA is replicated.

Passive transport processes move ions or molecules across the plasmalemma without any energy expenditure by the cell whereas active transport processes involve the cell spending energy.

During diffusion a molecule moves from an area of high concentration to an area of low concentration. Movement is achieved following the concentration gradient and no energy is spent by cell.

Receptor-mediated endocytosis is a process that resembles pinocytosis but is far more selective and only allows the entry of specific molecules into the cell. Target substances are bound to receptors on the membrane surface and brought into the cell via coated vesicles.

A cell does not have to have a nucleus. Prokaryotic cells are characterized by the fact that they don't have a nucleus nor any other membrane-bound organelles. However the rest of the statements are true of all cells and comprise cell theory.

Bacterial cells have cell membranes, cell walls, chromosomes, cytoplasm, and ribosomes. They may have flagella or cilia as well. They do not contain any membrane-bound organelles, such as the nucleus, endoplasmic reticulum, or mitochondria.

Cellular respiration is composed of many steps used to break down glucose and convert the chemical energy into ATP. Of the four steps described in the answer choices, oxidative phosphorylation via the electron transport chain is the most effective step for producing ATP. The electron transport chain can produce between 32 and 38 ATP from a single glucose molecule.

Glycolysis is the first step of glucose breakdown in cells. This process takes place in the cytosol.

The second step of cellular respiration, the citric acid cycle, takes place in the mitochondrial matrix. The third step, the electron transport chain, takes place on the inner mitochondrial membrane and requires protons to be concentrated within the intermembrane space.

Glycolysis is the first step in cell metabolism. It is responsible for converting glucose (a 6-carbon sugar) into two molecules of pyruvate (a 3-carbon sugar). Glycolysis occurs in the cytoplasm, where the sugar molecules interact directly with enzymes. After pyruvate is created, it is transported to the mitochondria for the remainder of cellular respiration (the citric acid cycle and electron transport chain).

Though plants undergo photosynthesis, they also use cellular respiration. Glycolysis takes place in both animal and plant cells.

Photosynthesis is the process by which plants use the sun's energy to convert water and carbon dioxide into glucose and oxygen .