AP Bio

What cellular structure helps form the cleavage furrow in animal cells?

The cleavage furrow in animal cells and the phragmoplast in plant cells are complex structures made up of microtubules and microfilaments that aide in the final separation of the cells into two identical daughter cells.

How do receptor proteins in a membrane act like enzymes?

When a receptor protein in a cell membrane acts as an enzyme, the receptor protein it activates a second messenger that acts as a signal molecule within the cell

How do phospholipids in the cell membrane move?

...

How does one rotting piece of fruit affect the ripening of others?

...

If the spindle can not form, at what stage will mitosis no longer proceed?

...

In what organisms is cell signaling less important?

...

What is a karyotype?

A karyotype is simply a picture of a person's chromosomes. In order to get this picture, the chromosomes are isolated, stained, and examined under the microscope. Most often, this is done using the chromosomes in the white blood cells. A picture of the chromosomes is taken through the microscope.

What chemical in animal cell membranes maintains their fluid nature?

A major chemical that regulates the fluidity of animal cell membranes by stiffening the membrane at higher temperatures and preventing the membrane from freezing at lower temperature is: cholesterol, lipid in nature, and a steroid.

What is the function of glycolipids & glycoproteins in animal cell membranes?

A major function of glycoproteins and glycolipids in the cell membrane is to allow the cells of an embryo to sort themselves into tissues and organs.

How do bacterial cells differ from animal cells?

Bacteria cells are prokaryotic meaning they have no membrane bound nucleus or membrane bound organelles which a plant or animal cell would, bacteria have DNA which is in a colied 'loop' within the cytoplasm aong with the ribosomes. The cell wall also differs from that in a plant or animal cell as it is made from peptidoglycan rather than cellulose. Some bacteria can have an undilipodium or flagella (tail). Prokaryotes get their energy from a mesosome which is situated at the cell membrane. Plant cells and Animal Cells are eukaryotic - Have nucleus, and membrane bound organelles and a cellulose cell wall, no undilipodium.

Describe the interor of chloroplasts & mitochondria.

Both organelles are bounded by an external membrane that serves as a barrier by blocking the passage of cytoplasmic proteins into the organelle. An inner membrane provides an additional barrier that is impermeable even to small ions such as protons. The membranes of both organelles have a lipid bilayer construction (see above Chemical composition and membrane structure). Located between the inner and outer membranes is the intermembrane space. In mitochondria the inner membrane is elaborately folded into structures called cristae that dramatically increase the surface area of the membrane. In contrast, the inner membrane of chloroplasts is relatively smooth. However, within this membrane is yet another series of folded membranes that form a set of flattened, disklike sacs called thylakoids. The space enclosed by the inner membrane is called the matrix in mitochondria and the stroma in chloroplasts. Both spaces are filled with a fluid containing a rich mixture of metabolic products, enzymes, and ions. Enclosed by the thylakoid membrane of the chloroplast is the thylakoid space. The extraordinary chemical capabilities of the two organelles lie in the cristae and the thylakoids. Both membranes are studded with enzymatic proteins either traversing the bilayer or dissolved within the bilayer. These proteins contribute to the production of energy by transporting material across the membranes and by serving as electron carriers in important oxidation-reduction reactions.

What effect would calcium deficiency have on a plant?

Calcium (Ca) deficiency is a plant disorder that can be caused by insufficient calcium in the growing medium, but is more frequently a product of low transpiration of the whole plant or more commonly the affected tissue. Plants are susceptible to such localized calcium deficiencies in low or nontranspiring tissues because calcium is not transported in the phloem.[1] This may be due to water shortages, which slow the transportation of calcium to the plant, poor uptake of calcium through the stem,[2] or can be caused by excessive usage of potassium or nitrogen fertilizers.[citation needed]

What occurs during prophase of mitosis?

Changes that occur in a cell during prophase: Chromatin fibers become coiled into chromosomes with each chromosome having two chromatids joined at a centromere. The mitotic spindle, composed of microtubules and proteins, forms in the cytoplasm.

By what process do large solids move into a cell?

Endocytosis: A cellular process in which large particles, solid or dissolved, outside the cell are surrounded by a fold of the plasma membrane, which pinches off, forming a vesicle, and the enclosed particle now moves into the cell; the three types of endocytosis are phagocytosis, pinocytosis, and receptor-mediated endocytosis. [Gk., endon, within + kutos, container]

What is the function of tyrosine-kinase receptors?

Enzymatic phosphorylation of tyrosine in the receptor protein

Why are eukaryotic cells larger than prokaryotic cells?

Eukaryotic cells are generally bigger than prokaryotic cells. This allows eukaryotes to have organelles, have slower turnover rates of macromolecules, and requires the presence of mechanisms to move things around the cell. The division of the chromosome from the rest of the cell and the larger size of eukaryotes, slows the rate at which they can replicate. The presence of organelles, which are sensitive to harsh conditions, might limit the extreme environments in which eukaryotes can grow.

What type of cells do not reproduce more cells by mitosis & cytokinesis?

Gametes, eggs and sperm, are from tissue that makes them and after they do not divide.

Through what type of junctions do ions travel between cells?

Gap junctions are intercellular channels some 1.5-2 nm in diameter. These permit the free passage between the cells of ions and small molecules (up to a molecular weight of about 1000 daltons). They are cylinders constructed from 6 copies of transmembrane proteins called connexins. Because ions can flow through them, gap junctions permit changes in membrane potential to pass from cell to cell.

Does the cytoskeleton limit cell size?

How does the surface area/volume ratio limit cell size? Cell surface area is used for import and export of important molecules. Volume increases with size more quickly than surface area, so size can only increase as long as surface area is still adequate.

Does the movement of oxygen & carbon dioxide across cell membranes require energy?

In addition to facilitated diffusion, cells are able to move big and/or charged molecules through membrane proteins against, or up, the molecules' concentration gradients. Impressive. Because doing this goes against the natural flow of molecules down their concentration gradients, cells must put energy into the process, generally in the form of ATP. Who knew ATP was so darn useful? For this reason, the movement of molecules up their concentration gradient is called active transport.

Besides the nucleus, where else can DNA be found in a cell?

In mitochondria and plant chloroplasts.

How do daughter & parent cells compare with each other?

In somatic cells, ( regular body cells) the daughter cells genetically identical to the parent cells because during mitosis, the chromosomes will replicate and create two sister chromatids. These will separate at the end of mitosis to create an identical cell. In Gamete cell (reproductive cells), the daughter cells are genetically different because of crossing over (genetic combination between two chromosomes) and independent assortment (random orientation of the pairs of homologous chromosomes at the metaphase plate of meiosis 1).

What is membrane potential?

Membrane potential (also transmembrane potential or membrane voltage) is the difference in electric potential between the interior and the exterior of a biological cell. With respect to the exterior of the cell, typical values of membrane potential range from -40 mV to -80 mV.

What will be true of cells that undergo mitosis but not cytokinesis?

Mitosis is nuclear division plus cytokinesis, and produces two identical daughter cells during prophase, prometaphase, metaphase, anaphase, and telophase. If there is no cytokinesis there will be no two identical cell produce

Name all structures in a cell responsible for movement.

On the outer surface of the cell, there are finger like projections called Cilia. Filaments in Cilia propel the cells movement by using ATP as energy source. Ciliated based movement is common and prokaryote.

Describe paracrine signaling

Paracrine signaling is a form of cell-cell communication in which a cell produces a signal to induce changes in nearby cells, altering the behavior or differentiation of those cells.

How is synaptic signaling different than hormone signaling?

Synaptic signaling is a response in your brain. It is the communication between your neurons(cells) in your brain. Hormone signaling is the communication between your hormones to keep your body's hormone regulated.

Name the parts of the cytoskeleton.

The cytoskeleton is a series of intercellular proteins that help a cell with shape, support, and movement. Cytoskeleton has three main structural components: microfilaments, intermediate filaments, and microtubules. The cytoskeleton mediates movement by helping the cell move in its environment and mediating the movement of the cell's components. Microfilaments are the smallest component of the cytoskeleton at about 7 nanometers in diameter. They are composed of G-actin protein and are wound in a helical shape. Intermediate filaments are 8-12 nanometers in diameter and are twisted together in a cord shape. They are composed of keratin and keratin-like proteins. These filaments are tough and resist tension. Microtubules are composed of alpha and beta tubulin that form long, hollow cylinders. These are fairly strong proteins and are the largest component of cytoskeleton at 25 nanometers. Tubular monomers can be lengthened or shortened from the positive end.

What protein makes up the cytoskeleton & gives a cell the shape?

The cytoskeleton of eukaryotic cells is made of filamentous proteins, and it provides mechanical support to the cell and its cytoplasmic constituents. All cytoskeletons consist of three major classes of elements that differ in size and in protein composition. Microtubules are the largest type of filament, with a diameter of about 25 nanometers (nm), and they are composed of a protein called tubulin. Actin filaments are the smallest type, with a diameter of only about 6 nm, and they are made of a protein called actin. Intermediate filaments, as their name suggests, are mid-sized, with a diameter of about 10 nm. Unlike actin filaments and microtubules, intermediate filaments are constructed from a number of different subunit proteins.

When the signal molecule changes the protein receptor, what process begins?

The process of transduction usually begins.

What is the purpose of cell fractionalism

The purpose of cell fractionation is to obtain a pure sample of part of the original whole, such as mitochondria, plasma membranes, DNA, RNA, soluble proteins or even a specific macromolecules

What cell organelles have two membranes?

The two organelles bounded by two membranes are the mitochondrion and the chloroplast.Both of them have their own outer and inner membranes which function for protection.

How can you determine if a karyotype is from a male or female?

To distinguish whether a person is male or female, there are two types of chromosomes that highlight this;an X chromosome and Y chromosome. In order for a person to be a male, you need to have one X and one Y chromosome. To be female, you need two X chromosomes.

How do genetic differences in clones occur?

Yes. In nature, some plants and single-celled organisms, such as bacteria, produce genetically identical offspring through a process called asexual reproduction. In asexual reproduction, a new individual is generated from a copy of a single cell from the parent organism. Natural clones, also known as identical twins, occur in humans and other mammals. These twins are produced when a fertilized egg splits, creating two or more embryos that carry almost identical DNA. Identical twins have nearly the same genetic makeup as each other, but they are genetically different from either parent.