Ch 3 A&P Flashcards
What is the cell theory?
All life forms are made from one or more cells
Cells only arise from pre-existing cells
The cell is the smallest form of life
Each cell maintains homeostasis
What is a cell composed of?
Cell membrane
Cytoplasm
Nucleus
what is the cell membrane?
The cell membrane forms the outer boundary of the cell and surrounds the cytoplasm, organelles, and nucleus.
It is also called the plasma membrane
What is the cytoplasm?
Watery solution of minerals, gases, and organic molecules that is found between the cell membrane and the nucleus
What is the nucleus?
The nucleus is the control center of the cell because it contains the chromosomes
With the exception of mature red blood cells, all human cells have a nucleus
What are chromosomes and how many of them in the body?
46
The 46 chromosomes of a human cell are usually not visible; they are long threads called chromatin.
Chromosomes are made of DNA and protein
DNA is the genetic code for the characteristics and activities of the cell
What is phospholipid and what does it do?
Phospholipids have a polar phosphorus-containing end, or “head,” and a non-polar “tail” composed of hydrocarbon fatty acid chains.The polar “head” interacts with water and is said to be hydrophilic (water-loving).
The non-polar “tail” interacts only with other non-polar substances, avoiding water and charged particles; this end is hydrophobic (water-fearing).
The heads will always orient towards water (inside and outside of cell) and the tails will move away from water.
What does cholesterol do?
The presence of cholesterol decreases the fluidity of the membrane, thus making it more stable.
What functions do proteins do?
Pores or openings to permit passage of materials
Enzymes that help substances enter the cell
Antigens or markers that identify the cells as “self”
Receptor sites for hormones
What are carbs (oligosaccharides) and what do they do?
In general, carbohydrates serve as markers and help in the recognition of certain substances.
Marks and help in the recognition of certain substances
Determine blood groups
Provides binding sites for certain toxins
Allows sperm to recognize the egg
Determines cellular life span
Serves in the immune response
Helps guide embryonic development
What is the nucleus and functions?
The nucleus is the control center of the cell because it contains the chromosomes
The Nucleus
The nucleus is within the cytoplasm and is bounded by a double-layered nuclear membrane with many pores.
It contains the nucleolus and the chromosomes of the cell.
A nucleolus is a small sphere made of deoxyribonucleic acid (DNA), ribonucleic acid (RNA), and protein.
The nucleoli form a type of RNA called ribosomal RNA, which becomes part of ribosomes (a cell organelle) and is involved in protein synthesis.
what is the functions of DNA?
DNA is a double strand of nucleotides (sugar, phosphate, and a nitrogen-containing base) in the form of a double helix, very much like a spiral ladder.
The rungs of the ladder are made of the four nitrogenous bases.
Although DNA contains just these four bases, the bases may be arranged in many different sequences (reading up or down the ladder).
It is the sequence of bases that is the genetic code.
The DNA of our 46 chromosomes is estimated to contain about 6 billion base pairs, which make up as many as 50,000 to 100,000 genes.
Recall that a gene is the genetic code for one protein, and a protein is a specific sequence of amino acids.
Therefore, a gene, or segment of DNA, is the code for the sequence of amino acids in a particular protein.
what are the functions of RNA?
The transcription of the genetic code in DNA into proteins requires the other nucleic acid, RNA
DNA is found in the chromosomes in the nucleus of the cell, but the production of protein takes place on the ribosomes in the cytoplasm.
Messenger RNA (mRNA) is the intermediary molecule between these two sites.
What is ATP and what does it stand for?
adenosine tri-phosphate
ATP transfers the potential energy in food molecules to cell processes.
All cells have enzymes that can breakdown ATP to release its energy.
What is endoplasmic reticulum and its function?
The endoplasmic reticulum (ER) is an extensive network of membranous tubules that extend from the nuclear membrane to the cell membrane.
Rough ER has numerous ribosomes on its surface, while smooth ER has no ribosomes at all.
As a network of interconnected tunnels, the ER serves as a passageway for the transport of the materials necessary for cell function within the cell.
These include proteins created by the ribosomes on the rough ER and lipids created by the smooth ER.
What are ribosomes?
Ribosomes are very small structures made of protein and ribosomal RNA.
Some are found on the surface of rough ER, while others float freely within the cytoplasm.
Ribosomes are the site of protein synthesis.
What is the golgi apparatus?
The Golgi apparatus is a series of flat, membranous sacs, somewhat like a stack of saucers.
Carbohydrates are synthesized within the Golgi apparatus and are packaged, along with other materials, for secretion from the cell.
To secrete a substance, small sacs of the Golgi membrane break off and fuse with the cell membrane, releasing the substance to the exterior of the cell.