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BIO1000 Human Biology Midterm 1Questions with Correct and Verified Answers Newest 2025-2026 Update Guaranteed Pass-Capella University
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What are the different mechanisms of horizontal gene transfer. [Knowledge, Comprehension] Transformation Transduction Conjugation Transformation a form of genetic recombination in which a DNA fragment from a dead, degraded bacterium (enters a competent recipient bacterium and is exchanged for a piece of DNA of the recipient). Transduction
the process by which a virus transfers genetic material from one bacterium to another. Viruses called bacteriophages are able to infect bacterial cells and use them as hosts to make more viruses. After multiplying, these viruses assemble and occasionally remove a portion of the host cell's bacterial DNA. Later, when one of these bacteriophages infects a new host cell, this piece of bacterial DNA may be incorporated into the genome of the new host. Conjugation the process by which one bacterium transfers genetic material to another through direct contact. During conjugation, one bacterium serves as the donor of the genetic material, and the other serves as the recipient. Describe the structure and function of the eukaryotic cell and its organelles (including nucleus and other elements of the endomembrane system, lysosomes, mitochondria, chloroplasts). [Knowledge, Comprehension] Nucleus Endoplasmic reticulum (Smooth and rough) Golgi Complex Plasma membrane Lysosome Vesicle Nuclear membrane/ envelope Mitochondria Chloroplast Nucleolus
Golgi Complex a stack of flattened , membranous sacs (without attached ribosomes) known as cisternae. It "tags" proteins - sorting to their final destinations. Protein modification (glycoprotein, lipoprotein). Plasma membrane a bilayer made of lipids with embedded protein molecules. Lysosome small, membrane bound vesicles that contain more than 30 hydrolytic enzymes for the digestion of many complex molecules. Responsible for Autophagy - recycling cell components. Degrade macromolecules (polymers), no longer required by the cell, to monomers. Monomers (e.g. amino acids) released to cytosol to be re-used. Also play a role in phagocytosis (some types of cells engulf bacteria or other cellular debris to break them down). Vesicle a small, membrane-bound compartment that transfers substances between parts of the endomembrane system (ex central vacuole, secretory vesicles) Nuclear membrane/ envelope
Nuclear membrane physically separates the genetic material from the rest of the cell. Double membranes (inner and outer nuclear membrane) connected with ER. Ribosomes on outer nuclear membrane. Has nuclear pore complex- Protein channel regulating nuclear entering and exiting. Mitochondria Membrane-bound organelles in which cellular respiration occurs. Double Membrane- bound organelles in which cellular respiration occurs. Mitochondrion contains its own DNA and ribosomes. Function: ATP generation- Act as a power plant of the cell. Chloroplast double membrane-bound organelles in which photosynthesis occurs. Surrounded by an outer and an inner membrane which completely enclose an inner compartment, the stroma. Within the stroma is a third membrane system consisting of flattened, closed sacs (thylakoids), on where photosynthesis takes place. Chloroplast contains its own DNA and ribosomes. Nucleolus a non-membrane bound structure composed of proteins and nucleic acids found within the nucleus. Ribosome
Endocytosis: Materials from the cell exterior are enclosed in a segment of the plasma membrane that pockets inward and pinches off as an endocytic vesicle (are then often digested by lysosomes). Describe the extracellular structures of animal and plant cells. [Comprehension] Most animal cells release materials into the extracellular space, creating a complex meshwork of proteins and carbohydrates called the extracellular matrix (ECM). A major component of the extracellular matrix is the protein collagen. Collagen proteins are modified with carbohydrates, and once they're released from the cell, they assemble into long fibers called collagen fibrils. List and describe the major eukaryotic cytoskeletal elements and associated motor proteins, their basic structure and their roles in the cell/organism. [Knowledge, Comprehension] Microtubules Intermeidate filaments Microfilaments Compare and contrast kinesin, dynein and myosin [Analysis]. Given a description of a cellular process predict which motor protein is involved. [Application, Evaluation] Kinesin and myosin walk to the plus end and require the hydrolysis of ATP. Dynein walks to the minus end. Kinesin and dynein both transport vesicles and organelles across microtubules. Myosin slides/ moves on microfilaments. Neither work on intermediate filaments. Actin and myosin are involved in muscle contractions.
Compare and contrast cells of bacteria, archaea and eukaryotes, identifying similarities and key differences (including DNA organization) between the cells of organisms from the different domains. [Comprehension, Analysis] Major differences between eukaryotic cells and prokaryotic cells:
the total potential energy of a system. Internal/ system energy Entropy (S) the tendency of energy to become dispersed or spread out. The measure of energy dispersal Exergonic a spontaneous process, the free energy of the products is less than the free energy of the reactants. Delta G is negative. Endergonic a nonspontaneous process, the free energy of the products is greater than the free energy of the reactants. Delta G is positive. (Gibbs) Free energy (Delta G) The mathematical relationship of how entropy and enthalpy relate to reaction spontaneity. Portion of a system's energy that is available to do work (convertible energy). Activated carrier molecule
Activated carriers are molecules that can be split (C โโ A + B) to release free energy (spontaneous). (ex ATP) Activation energy the initial energy investment required to start a reaction. Energy required to get a reactant to the transition state to start a reaction. Active site the specific site on an enzyme where catalysis takes place. Substrate the reactant that an enzyme acts on. Reactants the atoms or molecules entering a chemical reaction. Catalysis the acceleration of a chemical reaction by a catalyst.
Photopigment Light absorbing pigment (ex retinal), within a photoreceptor Photopsins are the photoreceptor proteins found in the cone cells of the retina that are the basis of color vision. (Come opsins L, M, S) Explain two major functions of light in living systems; compare and contrast the different ways that light can interact with matter. Light can be a source of energy (indirectly or directly). If the energy of a photon matches the amount of energy needed to move a molecule's electron from it's ground state to a specific excited state then that photon can be absorbed by the molecule. Once absorbed it can be used as a source of energy. Light enters the biosphere through photosynthesis (and then cellular respiration). Light can be a source of information. Photoreceptors are crucial to this, they contain a pigment that changes shape which triggers the proteins to change shape and in turn trigger downstream events (often including electrical signals used by the brain). Light can be reflected, transmitted or absorbed by an object. Only when light is absorbed can it be used as a source of energy. When a wavelength of light is transmitted or reflected that wavelength dictates the colour that object appears to our eyes. Describe the general physiology of the human eye (camera eye), and how light is sensed.
As light enters through the transparent cornea, a lens concentrates the light and focuses it onto a layer of photoreceptor cells at the back of the eye, the retina (made up of rod- intensity and cone- colour cells).The photoreceptor cells send information to the brain through the optic nerve. Describe how organisms can sense light with image-forming eyes (including structure and function of photoreceptors). With image forming eyes: Compound eyes: Built of hundreds of units called ommatidia fitted closely together. Each ommatidia samples only a small part of the visual field, with incoming light being focused onto a bundle of photoreceptor cells. From these signals the brain receives a mosaic of the world. Compound eyes are very good at detecting movement (because any movement is detected simultaneously by many ommatidia). Single lens/ camera eye: See above for general information. The retina has two types of photoreceptors; rod and cone cells. Rod cells sense light intensity, are sensitive to low levels of light and are x20 more abundant that cone cells. The outer portion of these cells are built of disks, each disk has membrane bound photopigment molecules called rhodopsin. Rhodopsin is made up of two parts; a membrane protein compound called opsin and a single pigment molecule called retinal (non-protein). When light is absorbed by the retinal it changes shape from a cis to trans conformation which trigger alterations to the opsin protein which trigger neurotransmitter release. Cone cells in the retina of the eye allow light of different wavelengths to be interpreted as color in the brain. Different cone cells contain different photopsins for different color detection. There are three types of photopsin proteins in cone cells; opsin S (shortwave blue light), opsin M (medium wave green light), opsin L (long wave red light). An individual possessing S, M and L opsins will have trichromatic vision. An individual possessing only S and M opsins will have dichromatic vision (and is colour blind).
Nucleoid the DNA containing central region of prokaryotic cells (bacteria and archaea). It has no boundary membrane separating it from the cytoplasm. Nucleus a membrane- bound (actually double membrane) compartment where the DNA is contained. Chromosome (eukaryotes) one complete DNA molecule (nucleic acid) with its associated proteins (such as packaging proteins), high order of DNA organization. Carries genetic information in the form of genes. 46 chromosomes total in humans. Chromosome (prokaryotes) one circular strand of DNA, the nucleoid. Plasmid Extrachromosomal small circular DNA molecules, often more than one copy. Carry non-essential genes but genes with beneficial functions (antibiotic resistance, metabolism, toxins etc.). Replicate independently of the chromosomal DNA.
Organelle small, organized structures important for cell function. Membrane a microscopic double layer of lipids and proteins that bounds cells and organelles and forms structures within cells. Plasma membrane a bilayer made of lipids with embedded protein molecules. Endomembrane system Collection of interrelated internal membranous sacs that divide cell into functional and structural compartments. Functions : 1. Synthesis, modification, transport and secretion of proteins 2. Synthesis of lipids and detoxification of toxins 3. Transportation and breakdown (digesting) of large biomolecule containing particles. Includes: Nuclear membrane/envelope, Endoplasmic reticulum, Golgi complex, Plasma membrane, Lysosomes, Vesicles Cytoskeleton a protein based framework of filamentous structures that among other things, helps maintain proper cell shape and plays key roles in cell division and chromosome segregation from cell generation to cell generation. Function of the cytoskeleton is structural support, shape, and motility.
Cell junction seal the spaces between cells and provide direct communication between cells. Anchoring junctions button-like spots or belts that run entirely around cells, welding adjacent cells together. Adjoining cells adhere at a mass of proteins anchored by many intermediate filaments (adherens junction) or microfilaments (desmosome) of the cytoskeleton. Tight junctions regions of tight connection between membranes of adjacent cells. Tight connections form between adjacent cells by fusing off plasma membrane proteins on their outer surfaces. A complex network of junction proteins makes a seal tight enough to prevent leaks of ions or molecules between cells. Gap junctions open direct channels that allow ions and small molecules to pass directly from one cell to another. Cylindrical arrays of proteins form direct channels that allow small molecules and ions to flow between the cytoplasm of adjacent cells. Genes segments of DNA that code for individual proteins.
Phototrophs Use light as source of energy for photosynthesis. Chemotrophs Use organic or inorganic substances as a source of energy. Heterotrophs Obtain carbon from consuming and breaking down carbon-containing organic molecules (sugar, lipid, amino acids etc). Autotrophs: Use inorganic carbon (CO2) to synthesize organic carbon molecules. Property of life ability to grow, reproduce, and respond to stimuli in a coordinated, potentially independent fashion. Euchromatin active transcription
