Biology Exam

Steps of investigating a natural phenomenon; includes observation, hypothesis formation, prediction, experimentation, analysis, and conclusion.

A testable explanation for an observation or phenomenon.

The variable that is changed or manipulated by the researcher in an experiment.

The variable that is measured or observed in response to changes in the independent variable.

Multiple trials of an experiment.

Proteins have four levels of structure: primary, secondary, tertiary, and quaternary. The primary structure is the linear sequence of amino acids. The secondary structure refers to local folding patterns, such as alpha helices and beta sheets. The tertiary structure describes the overall three-dimensional shape of a single polypeptide chain. The quaternary structure arises when multiple polypeptide chains assemble into a functional protein complex.

Factors affecting protein folding include: interactions between amino acid side chains (hydrophobic, electrostatic, hydrogen bonding), chaperone proteins that assist in proper folding, and environmental conditions such as temperature and pH.

Denaturation is the process of disrupting the three-dimensional structure of a protein, often leading to loss of function. This can be caused by factors like heat, extreme pH, or chemicals.

DNA (deoxyribonucleic acid) and RNA (ribonucleic acid) are both nucleic acids, but they differ in their structure and function. DNA is double-stranded and contains deoxyribose sugar, while RNA is single-stranded and contains ribose sugar. DNA stores genetic information, while RNA plays a role in protein synthesis.

Prokaryotic cells lack a nucleus and other membrane-bound organelles, while eukaryotic cells have a nucleus and other organelles. Prokaryotes are generally smaller and simpler than eukaryotes.

Plant cells have cell walls, chloroplasts for photosynthesis, and large central vacuoles, which are absent in animal cells. Animal cells contain lysosomes for cellular digestion.

Biological membranes are composed of phospholipids, forming a bilayer, with embedded proteins. Glycoproteins and glycolipids are also important components, playing roles in cell recognition and signaling.

Membrane proteins can be transmembrane (span the membrane), lipid-anchored (covalently attached), peripheral (noncovalently attached), or bound to the extracellular matrix or cytoskeleton.

Passive transport is the movement of molecules across a membrane without requiring energy. It can be simple diffusion (movement down the concentration gradient) or facilitated diffusion (movement down the gradient with the help of a protein).

Active transport is the movement of molecules across a membrane against their concentration gradient, requiring energy. It uses specialized proteins and energy sources like ATP.

The failure of homologous chromosomes or sister chromatids to separate properly during cell division (meiosis or mitosis), resulting in an abnormal number of chromosomes in the daughter cells.

A condition where a cell or organism has an abnormal number of chromosomes, either fewer or more than the typical diploid number.

A condition where a cell or organism has more than two sets of chromosomes (more than the typical diploid number).

Exchanging genetic material between homologous chromosomes during meiosis (crossing over) increases genetic diversity by creating new combinations of alleles. This genetic diversity is essential for populations to adapt to changing environments and resist diseases.

Organisms that consistently produce offspring with the same trait when self-fertilized, meaning they have two identical alleles for that trait.

An offspring resulting from the cross-breeding of two parents with different traits.

An individual with two identical alleles for a given trait.

An individual with two different alleles for a given trait.

One allele completely masks the expression of the other in a heterozygote, resulting in only the dominant phenotype being observed.

The phenotype of a heterozygote is an intermediate blend between the two homozygous phenotypes.

A phenotype that results from the combination of alleles from two different parents, through processes like crossing over or independent assortment.

A genetic map that shows the relative positions of genes on a chromosome, based on the frequency of recombination between them.

No. While most genes are located in the nucleus, some genes are found in organelles like mitochondria and chloroplasts.

Crossing over is a process that occurs during meiosis, where homologous chromosomes exchange genetic material. This exchange leads to genetic recombination, which creates new combinations of alleles and increases genetic diversity.

Inactivated X chromosomes in female mammals, forming a condensed, inactive structure within the nucleus.

DNA replication is semi-conservative, meaning each new DNA molecule contains one original strand and one newly synthesized strand.

Telomerase is an enzyme that adds repetitive DNA sequences (telomeres) to the ends of chromosomes, preventing degradation and maintaining chromosome integrity.

Telomerase ensures that the ends of linear chromosomes are fully replicated during DNA replication, preventing shortening and protecting the genetic information.

A change in a single nucleotide within a gene sequence.

A genetic mutation caused by the insertion or deletion of nucleotides, leading to a shift in the reading frame, altering the amino acid sequence.

A mutation that occurs naturally without any known external cause.

A mutation that occurs in a germ cell (sperm or egg), which can be passed on to offspring.

A genetic mutation that reduces or eliminates the activity of a gene.

The control of gene expression at the level of RNA transcription.

A type of operon that is activated by the presence of a specific inducer molecule. In the Lac operon, lactose acts as the inducer.

A DNA sequence located in the promoter region of eukaryotic genes that helps position RNA polymerase for transcription initiation.

Three methods of direct communication in animal and plant cells are: 1) Plasmodesmata (plant cells): cytoplasmic connections that allow for direct exchange of molecules. 2) Gap junctions (animal cells): channels that connect the cytoplasm of adjacent cells, facilitating direct exchange. 3) Cell-cell recognition: interactions between molecules on the surfaces of adjacent cells, allowing for communication and coordination.

Cell signaling can be divided into three phases: 1) Reception: The cell detects a signaling molecule (ligand) by binding it to a specific receptor protein. 2) Transduction: The binding of the ligand triggers a series of events inside the cell, converting the signal into a form that can elicit a cellular response. 3) Response: The signal is finally relayed to a specific target molecule or pathway, leading to a change in cell behavior.

Three categories of membrane proteins act as receptors in cell signaling: 1) G protein-coupled receptors (GPCRs): Utilize a G protein to relay the signal. 2) Enzyme-linked receptors: When activated, they can directly act as enzymes or activate other enzymes. 3) Ion channel receptors: Open or close to allow ions to flow across the membrane, changing the cell's electrical potential.

Intracellular receptors are located inside the cell and bind to signaling molecules that can cross the cell membrane. Membrane receptors, on the other hand, are embedded within the cell membrane and bind to signaling molecules that are too large or hydrophilic to cross the membrane. Intracellular receptors often influence gene expression, while membrane receptors activate signaling pathways within the cell.

Cellular responses to signaling molecules can be diverse: 1) Changes in gene expression: The signal may stimulate the production or repression of specific proteins. 2) Activation of enzymes: The signal can activate or inhibit specific enzymes within the cell. 3) Altered cell behavior: The signal can lead to changes in cell growth, movement, or other aspects of cellular function.

All viruses have two components: 1) Genetic material: either DNA or RNA. 2) Protein coat (capsid): surrounds and protects the genetic material. Some viruses also have an envelope: a membrane derived from the host cell that helps the virus enter cells.

Most scientists consider viruses to be non-living entities because: 1) They cannot reproduce independently and rely on host cells. 2) They lack the machinery and metabolic processes of living organisms. 3) They do not exhibit growth or development.

The lytic cycle is a viral replication process that destroys the host cell. 1) Attachment: The virus attaches to the host cell. 2) Entry: The viral genetic material enters the host cell. 3) Replication: The viral genome takes over the host's cellular machinery to produce new viral components. 4) Assembly: New viral particles are assembled. 5) Release: Newly formed viruses are released from the host cell, often lysing (bursting) it and releasing more viruses to infect other cells.

The lysogenic cycle is a viral replication process that allows the virus to remain dormant within the host cell. 1) Integration: The viral genome integrates into the host cell's DNA. 2) Replication: The viral genome is replicated along with the host cell's DNA. 3) Dormant: The virus may remain dormant for a period. 4) Induction: The virus can reactivate and enter the lytic cycle.

Retroviruses, like HIV, have a unique replication cycle: 1) Entry: The virus enters the host cell. 2) Reverse transcription: The viral RNA is converted into DNA using reverse transcriptase. 3) Integration: The viral DNA integrates into the host cell's genome. 4) Replication: The integrated viral DNA is replicated along with the host cell's DNA. 5) Transcription and translation: The integrated viral DNA is transcribed into viral RNA and translated into viral proteins. 6) Assembly and release: New viral particles are assembled and released from the host cell.