Chapter 3 Reading Guide
Overview
This reading guide is intended to be used with the Open Stax Anatomy and Physiology textbook
Open Stax Anatomy and Physiology Chapter 3 Reading Guide
Human Anatomy and Physiology
Chapter 3: The Cellular Level of Organization
3.1: The Cell Membrane
Chapter 3: The Cellular Level of Organization
Structure and Composition of the Cell Membrane
- ______________ – boundary of the cell.
- Made up of phospholipid molecules organized into a bilayer.
- The presence of cholesterol contributes to the membrane's fluidity.
- Various embedded proteins have a wide range of functions.
- Structure of a phospholipid molecule
- Phosphate head is ___________, attracted to water molecules, dissolves freely in water
- Two fatty acid tails attached to the head are ______________, water-fearing, repel water molecules, will not dissolve in water.
- __________________________ having both a hydrophilic and hydrophobic region.
- Soap has amphipathic properties to remove oil and grease stains.
- Cell membrane consists of two adjacent layers of phospholipids arranged into a ________________________.
- The cell membrane separates ICF (__________________) from ECF (______________________) the fluid outside of the cell membrane. IF (________________) is extracellular fluid outside of blood vessels.
Membrane Proteins
- ____________________ – a membrane protein embedded in the cell membrane.
- _________ – binds specific molecules (ligands) outside of the cell that induces a chemical reaction inside of the cell.
- _________ - a specific molecule that binds to and activates a specific receptor
- _________ – a protein with carbohydrate molecules attached, which extend into the extracellular matrix. Function in cell recognition, identify as self, immune responses.
- _______________ – a coating around the cell made up of glycoproteins and glycolipids attached to the outside of the cell membrane
- _____________ – any integral protein that selective allows specific materials to pass into or out of the cell
- ____________________ – attached to either the inside or outside surface of the cell membrane. Perform various functions, see text.
Cell Membrane
Transport across the Cell Membrane
- __________________ – the cell membrane regulates molecular traffic going inside and outside the cell.
- Passive vs Active Transport
- ________________ – The spontaneous movement of substances without the expenditure of cellular energy.
- _______________ – requires cellular energy usually in the form of ATP.
Passive Transport
- ___________________________ – the difference in concentration of a substance across a space.
- Molecules (or ions) will spread out from a region of high concentration to where they are less concentrated. Move down the concentration gradient.
- _______________ – the movement of particles down the concentration gradient.
- ____________________ – the diffusion process that is used for those substances that cannot cross the membrane due to size, charge, and polarity.
- ______________ – the diffusion of water across a semipermeable membrane.
- Movement of water inside or outside of cells is influenced by the concentration of solutes outside or inside of the cell.
- Water always diffuses from an area with fewer solutes towards an area of more solutes, thus diffusing down its concentration gradient.
- _________ – two solutions with equal concentration of solutes
- When a cell and its extracellular environment is isotonic, the concentration of water molecules is equal both inside and outside the cell.
- ____________ – an imbalance of solutes outside the cell relative to inside. When the concentration of solutes is greater outside than inside osmosis occurs and water will leave the cell.
- ________________ – when the concentration of solutes is less outside than inside, osmosis occurs, and water will enter the cell.
Active Transport
- Requires ATP and specific protein carriers to move substances against its concentration gradient.
- _______________________ or Na+/K+ ATPase, transports sodium out of the cell while moving potassium into the cell.
- This pump maintains an electrical gradient across cell membranes
- ____________________ – the difference in charge across a space.
- Bulk flow – active transport mechanisms that do not involve membrane carriers
- _______________ – cellular ingestion by enveloping the material in a portion of its cell membrane. Forms a membranous sac called a ____________.
- _____________ – cellular eating, like Pac Man, white blood cells ingesting bacteria or viruses.
- ________________ – cellular drinking of fluid with dissolved substances through vesicles.
- __________________________ - endocytosis by a portion of membrane that contains receptors that are specific for a certain substance.
- ___________ – cellular exporting material by vesicular transport. See text for details.
3.2: The Cytoplasm and Cellular Organelles
Chapter 3: The Cellular Level of Organization
- Basics of Cellular Structure
- _________ – semi fluid substance within the cell provides the fluid medium necessary for biochemical reactions to occur
- ___________ – most are membrane bounded, bodies inside the cell each performing a given function
- __________ – The cytosol and organelles together.
- ________ – the cell’s central organelle, which contains most of the cell’s DNA.
- Example of a typical human cell figure
Organelles of the Endomembrane System
- ____________________ – a system of channels that begins outside of the nuclear envelope, provides passages through the cell that function in transport, synthesizing and storage of materials.
- ___________ – its outer surface is covered with ____________ (the site of protein synthesis, synthesis, and modification of proteins
- __________ – not covered with ribosomes, production of membranes, breaking down toxins.
- _______________ – sorting, modifying and transportation of cellular products
- ___________ – contain digestive enzymes
- Breakdown and digest unneeded cellular components.
- ________________ – the process of a cell digesting its own structures
- _______________ – cellular self-destruct mechanism
Organelles for Energy Production and Detoxification
- _________________
- Carry out important energy transformation reactions that result in the production of ATP.
- Mitochondrion Structure
- Double membranes an outer lipid bilayer with an additional inner lipid bilayer.
- ____________– finger-like folds of the inner membrane with a great deal of surface area.
- ________________________
- A single membrane bound structure that contains enzymes for lipid metabolism and chemical detoxification
- Critical to the neutralization of free radical species
- Minimize the harm due to oxidative stress.
The Cytoskeleton
- _______________ – helps the cells to maintain their structural integrity.
- Composed of fibrous proteins
- Other functions
- Provide structural support to cells
- Cell motility
- Cell reproduction
- Transportation of substances within the cell.
- Positioning of cellular organelles (cytoplasmic streaming)
- The cytoskeleton is composed of three different kinds of protein-based filaments
- _______________
- Thickest of the three
- Composed of tubulin (a protein)
- Maintain cell shape and structure, resist compression of the cell
- Help position organelles inside the cell
- Make up cilia and flagella
- ____________ are found on the surface of cells, move like oars on a boat, move materials pass them
- ________________ are longer than cilia and specialized for cell locomotion, function much like a boat propeller.
- Set the path for chromosome movement during cell division
- Make up _______________which assist in moving chromosomes during cell division.
- _______________ – the thinnest type of cytoskeletal filaments formed of actin (a protein that forms chains).
- Carry out muscle contraction along with the protein myosin
- ______________________ – intermediate in thickness between microfilaments and microtubules
- Made up of long fibrous protein subunits much like a rope.
- Maintain cell shape and structure, resist tension.
- Anchor organelles together and link cells together via cell to cell junctions
3.3: The Nucleus and DNA Replication
Chapter 3: The Cellular Level of Organization
- ______________________
- The largest and most prominent cellular organelle.
- Considered the control center of the cell.
- Contains all the genetic instructions for manufacturing proteins and replicating the cell’s DNA content.
- Organization of the Nucleus and its DNA
- __________________ – two adjacent lipid bilayers that surround the contents of the nucleus
- _______________ – small passageways in the nuclear envelope for the passage of molecules
- _______________ – A region inside the nucleus that manufactures ribosomal RNA (rRNA) needed for the construction of ribosomal sub-units.
- _______________ – thin threads composed of DNA and histone proteins
- DNA winds around sets of histone proteins forming ________________________ which resemble beads on a string.
- A molecule of DNA is made up of multiple nucleosomes.
- _______________ – the condensed form of chromatin. Chromosomes form during cell division.
- Humans have an estimated 22,000 genes on 46 chromosomes.
DNA Replication
- Characteristics of DNA
- Two strands of nucleotides that are complementary, hydrogen bond to one another, and resembles a long-twisted ladder (DNA double helix).
- Each side rail of the DNA molecule is composed of alternating sugar and phosphate groups that form a backbone.
- Nitrogen containing bases are positioned on one side of the strands of nucleotides, meeting in the middle for complementary base pairing.
- A – T
- C – G
- The sequence of bases determines the genetic code.
- 3’ – AGTGCCT – 5’
- 5’ – TCACGGA – 3’
- _____________________ – a process by which DNA is copied prior to cell division.
- _______________________ – each new DNA molecule has one parent strand and one daughter strand.
- Stages of DNA Replication
- Stage 1: Initiation
- Two complementary strands are separated by the enzyme __________________.
- Stage 2: Elongation
- _______________________ – brings in the correct bases to complement the template strand to synthesize a new strand base by base.
- Stage 3: Termination
- Once replication stops, the two new identical DNA molecules are complete.
3.4: Protein Synthesis
Chapter 3: The Cellular Level of Organization
- DNA is the blueprint for cell structure and physiology.
- _____________ – the entire complement of a cell's DNA.
- __________________ – the complete complement of a cell’s proteins.
- ________________ – a DNA sequence that provides the instructions to build a specific protein.
- _________________________ – the process by which the instructions in a gene are translated into a final gene product.
- Gene interpretation steps
- _______________ – a section of DNA bases in a row that codes for a specific amino acid
- A single gene is composed of multiple triplets in a unique sequence.
From DNA to RNA: Transcription
- Occurs in the nucleus of cells
- DNA sequence for a single gene is copied into an intermediate messenger
- __________________ (mRNA)
- A single stranded nucleic acid that carries the copy of the genetic code from the nucleus to the cytoplasm.
- Comparison of DNA and RNA
- Double stranded vs single stranded
- Deoxyribose sugar vs ribose sugar (Ribose contains an additional oxygen atom)
- The base thymine is replaced by uracil
- ______________ is the synthesis of a strand of mRNA that is complementary to the gene transcribed.
- DNA triplets are transcribed into ________, which are three base sequences of mRNA that directly encode amino acids
- Stages of Transcription
- Stage 1: _____________
- Transcription begins at the beginning of the gene, at a sequence called the __________________.
- Stage 2: _________________
- ______________________ unwinds the DNA segment
- Then it aligns the correct base with its complementary base on the coding strand of DNA.
- RNA polymerase adds new nucleotides to the growing strand of mRNA
- Stage 3: _____________________
- The polymerase reaches the end of the gene
- One of three specific codons (UAA, UAG, or UGA) codes a stop signal.
- Enzymes are triggered to terminate transcription and release the mRNA transcript.
- mRNA modifications
- Occur in the nucleus after transcription but before translation in the cytoplasm.
- There are long regions that do not code for amino acids (________________). They must be removed before translation can take place.
- ________________ is the name of the process that removes introns and join ________________ (coding regions) together.
- A ___________________ is a structure that attaches to the pre mRNA and cuts out introns and joins the exons together into a single continuous RNA molecule.
From RNA to Protein: Translation
- ______________________ is the process of synthesizing a chain of amino acids called a _______________________.
- Occurs at the ribosomes
- Ribosomes are made of __________________ (rRNA) and proteins.
- Exist as two subunits (large and small) which come together for translation to occur.
- Also require a third type of RNA called ________________ (tRNA).
- tRNA reads the mRNA codons to insert amino acids in the correct place.
- _______________ is a sequence of 3 bases on tRNA that is complementary to the mRNA codon.
- Steps of translation
- _______________ – ribosome binds to mRNA transcript
- _______________ – Recognition of codon with anticodon, amino acids are joined by peptide bonds.
- ____________________ – occurs when a stop codon is reached. The polypeptide is released, and mRNA detaches from the ribosome.
3.5: Cell Growth and Division
Chapter 3: The Cellular Level of Organization
- Introduction to cell growth and division: important concepts
- _______________ – general term for body cells.
- ______________ – sperm and egg cells, and their progenitors.
- _________________________ – two copies of a single chromosome found in each somatic cell.
- ________________ – in humans it is having 23 homologous pairs or 46 chromosomes.
- _______________– having only one of a type of chromosome, in humans that is 23, which is the number of chromosomes found in an egg or a sperm cell.
- ___________________ – the sequence of events in the life of a cell from its creation until it divides itself.
The Cell Cycle
- Consists of Interphase and Mitosis
- _______________ – the period in which the cell is not dividing.
- ___________ – division of the nucleus
- Usually accompanied by __________________ or division of the cytoplasm.
- Mitosis and cytokinesis results in two distinctive cells.
- Interphase
- Divided into 3 separate periods
- _______________ – first gap phase, the cell grows and carry's out normal functions
- _______________ – the cell replicates its DNA
- ________________ – second gap phase, the cell continues to grow and prepare for mitosis.
- ______________ – a resting phase of the cell cycle, cells that have stopped dividing
The Structure of Chromosomes
- Prior to cell division
- Each cell contains two copies of each chromosome.
- Each copy is referred to as a ______________ and is attached to the other copy.
- The ________________ is the structure that attaches one sister chromatid to another.
Mitosis and Cytokinesis
- ___________ – the first phase of mitosis
- Chromatin condenses into chromosomes
- Each chromosome consists of two sister chromatids joined at the centromere.
- The nucleolus disappears along with the nuclear envelope.
- ________________ – consists of a single pair of centrioles together.
- The centrioles begin to move apart
- ___________________ begins to form between the two centrioles
- Spindle microtubules attach to the centromeres of the sister chromatids, to a protein structure on the centromere that is called the ___________________.
- ___________________– the second stage of mitosis
- The sister chromatids line up along an imaginary plane in the middle of the cell, named the _________________________.
- The spindle microtubules are poised to pull the sister chromatids apart to bring one from each pole to each side of the cell.
- ________________ – the third stage of mitosis
- The sister chromatids are pulled apart, forming individual chromosomes
- Each daughter chromosome moves to opposite sides of the cell.
- Each end of the cell receives one partner from each pair of sister chromatids.
- ___________________ – the final stage of mitosis
- Formation of daughter nuclei, nucleoli appear, mitotic spindle breaks down
- Cytokinesis occurs, cell is splitting in half around each daughter nucleus.
- ____________________ – a contractile band of microfilaments squeezes the two cells apart.
Cell Cycle Control
- An elaborate system of regulation which involves molecules inside the cell as well as external stimuli.
- This system provides stop and advance signals for the progression of the cell cycle.
- Mechanisms of Cell Cycle Control
- A __________________ is a point in the cell cycle at which a signal moves the cycle forward or stops it.
- Different molecules provide the signals to stop or go forward at each checkpoint.
- ____________ – is one of the primary classes of cell cycle control molecules.
- _____________________________ (CDK) – interact with cyclins to determine progression past cell checkpoints.
3.6: Cellular Differentiation
Chapter 3: The Cellular Level of Organization
- Stem Cells
- _____________ – an unspecialized cell that can divide without limit as needed, and differentiate into specialized cells
- Categories of Stem Cells
- ________________ – the first embryonic cells that arise from division of the zygote.
- These cells can become any of the cells needed for an organism to grow and develop.
- _______________ – a stem cell that has the potential to differentiate into any cell type, but cannot support full development of an organism
- ________________ – has the potential to differentiate into different types of cells within a given cell lineage.
- ________________ – a more specialized stem cell that is limited to becoming one of a few cell types
- _____________- can only form cells of its own specific cell type.
Differentiation
- Each type of cell only reads the portions of DNA that are relevant to its cell type.
- _________________________ – a class of proteins that can either promote or inhibit transcription of genes.