Module 3 Flashcards
cytoskeleton
a network of several kinds of protein filaments that extend throughout the cytoplasm and provide a structural framework for the cell.
cytoskeleton consists of
microfilaments, intermediate filaments, and microtubules.
microfilaments are composed of
Most microfilaments are composed of actin, and function in movement and mechanical support.
Intermediate filaments are composed of
Intermediate filaments are composed of several different proteins, and function in support and helping to anchor organelles such as the nucleus.
Microtubules are composed of
Microtubules are composed of a protein called tubulin, and help determine cell shape and function in the intracellular transport of organelles and the migration of chromosomes during cell division.
Centrosomes are
Centrosomes are dense areas of cytoplasm that contain the centrioles—the paired cylinders arranged at right angles to one another—that serve as centres for organizing microtubules in interphase cells and the mitotic spindle during cell division.
Cilia are
Cilia are numerous, short, hair-like projections extending from the surface of a cell, which function to move materials over the surface of cells located in the lining of the respiratory tract and fallopian tubes.
Flagella are
Flagella are similar to cilia but are much longer; usually, they move an entire cell. The only example of a flagellum in the human body is the tail of the sperm cell.
Ribosomes are
Ribosomes are tiny spheres that consist of ribosomal RNA and several ribosomal proteins; they occur free (singly or in clusters) or together with endoplasmic reticulum.
Ribosomes are the sites of
Ribosomes are the sites of protein synthesis.
The endoplasmic reticulum (ER) is
The endoplasmic reticulum (ER) is a network of membranes that form flattened sacs or tubules called cisterns.
Rough ER is
structure
Rough ER is continuous with the nuclear membrane and has an outer surface studded with ribosomes.
Smooth ER
Smooth ER extends from the rough ER to form a network of membrane tubules, but it does not contain ribosomes on its membrane surface.
ER function
The ER transports substances, stores newly synthesized molecules, synthesizes and packages molecules, detoxifies chemicals, and releases the calcium ions involved in muscle contraction.
The Golgi complex consists of
The Golgi complex consists of four-to-six stacked, flattened membranous sacs (cisterns) referred to as cis, medial, and trans.
The principal function of the Golgi complex is
The principal function of the Golgi complex is to process, sort, and deliver proteins and lipids to the plasma membrane, lysosomes, and secretory vesicles.
Lysosomes are
structure
Lysosomes are membrane-enclosed vesicles that form in the Golgi complex, and which contain powerful digestive enzymes.
Lysosomes function in
Lysosomes function in intracellular digestion, the digestion of worn-out organelles (autophagy), the digestion of cellular contents (autolysis) during embryological development, and extracellular digestion.
Peroxisomes are
Peroxisomes are similar in structure to, but are smaller than, lysosomes. Peroxisomes contain enzymes (e.g., catalase) that use molecular oxygen to oxidize various organic substances.
A proteasome is
A proteasome is a tiny membrane-bound sac that contains protease enzymes, which are able to cut proteins.
The mitochondrion is
structure
The mitochondrion is bound by a double membrane. The outer membrane is smooth, whereas the inner membrane is arranged in folds called cristae.
Mitochondria are the site of
Mitochondria are the site of ATP production in the cell through the catabolism of nutrient molecules.
Mitochondria self-replicate using their own DNA.
how many nucleus do cells have?
Most body cells have a single nucleus; some (red blood cells) have none; and others (skeletal muscle fibres) have several.
nucleus structure
The nucleus includes the nuclear envelope—which is perforated by channels called nuclear pores—the nucleoli, and genetic material (DNA).
what is inside the nucleus
Within the nucleus are located genes, the hereditary units of cells, which are arranged in single file along the chromosomes.
chromosome
Each chromosome is a long molecule of DNA that is coiled together with several proteins. Human somatic cells have 46 chromosomes arranged in 23 pairs.
The various levels of DNA packaging are represented by
The various levels of DNA packaging are represented by nucleosomes, chromatin fibres, loops, chromatids, and chromosomes.
Protein synthesis
Proteins determine the physical and chemical characteristics of cells. The instructions for protein synthesis are found in the DNA in the nucleus. Protein synthesis involves transcription and translation.
transcription
Transcription is the process by which the genetic information encoded in DNA is copied onto a strand of RNA called messenger RNA (mRNA), which directs the protein synthesis. Besides serving as the template for the synthesis of mRNA, DNA also synthesizes two other kinds of RNA—ribosomal RNA (rRNA) and transfer RNA (tRNA).
The transcription of DNA is catalyzed by
The transcription of DNA is catalyzed by RNA polymerase.
translation
Translation is the process of reading the mRNA nucleotide sequence to determine the amino acid sequence of the protein.
The sequence of translation is as follows:
- rRNA and proteins form ribosomes.
- Specific amino acids attach to molecules of tRNA. Another portion of the tRNA has a triplet of nitrogenous bases called an anticodon. A codon is a segment of three bases of mRNA.
- tRNA delivers a specific amino acid to the codon; the ribosome moves along an mRNA strand as amino acids are joined to form a growing polypeptide.
what is cell division
Cell division is the process by which cells reproduce themselves. It consists of nuclear division (mitosis and meiosis) and cytoplasmic division (cytokinesis).
somatic cell division
Cell division that results in an increase in body cells is called somatic cell division and involves a nuclear division called mitosis, plus cytokinesis.
reproductive cell division
Cell division that results in the production of sperm and eggs is called reproductive cell division and consists of a nuclear division called meiosis, plus cytokinesis.
The cell cycle is
The cell cycle is an orderly sequence of events by which a cell duplicates its contents and divides in two. It consists of interphase and the mitotic phase.
interphase
During interphase, the cell carries on every life process except division.
A cell in interphase shows a distinct nucleus and an absence of chromosomes.
mitosis
The mitotic phase consists of mitosis (or nuclear division) and cytokinesis (or cytoplasmic division).
Mitosis is the distribution of two sets of chromosomes, one set into each of two separate nuclei.
stages of mitosis
The stages of mitosis are prophase, metaphase, anaphase, and telophase
prophase
During prophase, the chromatin condenses and shortens into chromosomes, formed by two sister chromatids joined at the centromere.
metaphase
During metaphase, the centromeres line up at the exact centre of the mitotic spindle, a region called the metaphase plate or equatorial plane region.
anaphase
Anaphase is characterized by the splitting and separation of centromeres and the movement of the two sister chromatids of each pair toward opposite poles of the cell.
telophase
Telophase begins as soon as chromatid movement stops; the identical sets of chromosomes at opposite poles of the cell uncoil and revert to their threadlike chromatin form; microtubules disappear or change form; a new nuclear envelope forms; new nucleoli appear; and the new mitotic spindle eventually breaks up.
cytokinesis
Cytokinesis is the division of the cytoplasm and organelles of a parent cell. The process begins in late anaphase or early telophase with the formation of a cleavage furrow.
What are the components of a typical cell?
plasma (cell) membrane
cytoplasm (cytosol and organelles)
nucleus
What is the structure of the plasma membrane?
a phospholipid bilayer with hydrophobic lipid tails on the inside and the hydrophilic heads on the outside and inside of the cell.
What is in the phospholipid bilayer?
proteins (mainly glycoproteins)
What do the proteins in the phospholipid bilayer do?
channels (pores)
transporters (carriers)
receptors (recognition sites)
enzymes
What is the function of the plasma membrane?
to control the movement of particles into and out of the cell and to contain the cytoplasm
What is the outer coating of the plasma membrane called?
glycocalyx
What is the function and structure of the glycolcalyx?
formed by glycoproteins and glycolipids’ tails sticking out from the cell membrane
They make up the identity of a person’s cells.
What are the 3 forms of membrane transport?
selective permeability
active transport
passive transport
What is selective permeability?
only substances meeting a certain criteria may pass through unaided
What is passive transport?
movement of substances across the membrane without the expenditure of cellular energy
(O2 and CO2)
What is active transport?
movement of substances across the cell membrane using ATP
