Cell Biology - AP Biology

There are no homologous pairs in mitosis. Mitosis has sister chromatids that separate and result in two identical daughter cells. Meiosis has homologous pairs because it occurs in sex cells and has one chromosome from the father and the other from the mother. These chromosomes pair up in Metaphase I and then separate in Anaphase I. Mitosis occurs in somatic cells so there is only one chromosome made up of two sister chromatids that separate during Anaphase.

Crossing over occurs during Prophase I. During Prophase I, chromatin condenses and homologous chromosomes come together to form a tetrad. At this point, sometimes pieces of the chromatids within the chromosomes break off and exchange DNA. This process is known as "crossing over." This cannot occur in Prophase II because there are no homologous chromosomes in this stage, and therefore there isn't any different DNA to exchange.

During prophase, the cell will begin to condense its chromosomes to prepare for separation during anaphase. The pair of centrioles in the cell will also separate and begin to move towards opposite ends of the cell, while remaining attached to each chromosome by a microtubule. These fibers form the mitotic spindle, which organizes and repositions the chromosomes during cell division. During this phase, the nuclear envelope and nucleolus also break down and disappear.

The correct answer is "metaphase." The chromosomes are each attached to spindle fibers at the centromere. When the chromosomes align along the middle of the cell (often called the "metaphase plate"), the cell is in metaphase. Metaphase occurs after prophase (during which the cell grows and replicates its DNA) but before anaphase (when the chromosomes are pulled by spindle fibers to opposite ends of the cell).

A somatic (body) cell is always diploid, meaning that it has chromosomes. When a cell undergoes meiosis, the number of chromosomes in each daughter cell will be half the number in the original parent cell. Each daughter cell produced from meiosis will be haploid, meaning that it will have chromosomes.

A somatic (body) cell is always diploid, meaning that it has chromosomes. When a cell undergoes mitosis, the number of chromosomes in each daughter cell is the same as the number of chromosomes in the original parent cell. Each daughter cell produced from mitosis is diploid, meaning that it will have (in this case ) chromosomes.

A defining characteristic of prokaryotes is the lack of a true nucleus. Prokaryotic cells do contain ribosomes, DNA, and cell walls, and some but not all prokaryotes are capable of photosynthesis.

The rough endoplasmic reticulum is described as "rough" because it is covered in ribosomes, which look like tiny beads along its surface. The smooth endoplasmic reticulum doesn't have these ribosomes all over its surface, so it appears flat and is described as "smooth" for this reason. The ribosomes function to make proteins.

The endoplasmic reticulum is made up of membrane-enclosed spaces used for the trafficking of materials that will be secreted from the cell. Therefore it is involved in exocytosis, not endocytosis. The smooth ER is involved in metabolism and lipid synthesis. The rough ER contains ribosomes accounting for its rough appearance and allowing it to be involved in protein synthesis.

The Golgi aparatus does not synthesize lipids. Lipids are synthesized in the smooth ER.

The Na+/K+ pump is active transport and therefore requires ATP. Since the pump is moving ions against its concentration gradient, it requires ATP to change the conformation of the pump to release the ions. All of the other forms of transport are either diffusion (moving down its concentration gradient) or facilitated diffusion (moving down its concentration gradient with the help of a channel or carrier).

Good tip: Pumps are used for active transport while carrier proteins or channels are used for facilitated diffusion which is a type of passive transport.

Cells do not arise from nonliving substances, though scientists used to believe they did. Through several experiments by many different scientists, it became clear that indeed all cells arise from preexisting cells.

Plants, bacteria, and fungi have both a membrane as well as a cell wall. On the other hand, animal cells have only a membrane.

Plant cell walls are made of cellulose, a polysaccharide.

Bacterial cell walls are composed of peptidoglycan, a protein and sugar moiety.

Fungal cells have cell walls composed of chitin, a polysaccharide similar in structure to cellulose.

While the photosynthetic process differs slightly among these organisms, cyanobacteria, algae, and ferns (along with all other plants) all undergo photosynthesis-the process of using sunlight to synthesize food from carbon dioxide and water.

The electron transport chain is found on the inside of the inner mitochondrial membrane. It is not used to transport proteins; instead, it generates ATP to be used as an energy source by the cell. The electron transport chain is found in plants and animals (though the one found in plants operates very differently than the one found in animals). Oxygen is the final electron acceptor, not glucose.

The rough endoplasmic reticulum is described as "rough" because it is covered in ribosomes, which look like tiny beads along its surface. The smooth endoplasmic reticulum doesn't have these ribosomes all over its surface, so it appears flat and is described as "smooth" for this reason. The ribosomes function to make proteins.

The endoplasmic reticulum is made up of membrane-enclosed spaces used for the trafficking of materials that will be secreted from the cell. Therefore it is involved in exocytosis, not endocytosis. The smooth ER is involved in metabolism and lipid synthesis. The rough ER contains ribosomes accounting for its rough appearance and allowing it to be involved in protein synthesis.