Overview of Genetics, Cells, and the Cell Cycle

These flashcards cover key concepts from the lecture notes on genetics, cellular structure, organelle functions, and the cell cycle—emphasizing applications to dentistry and human health.

What does the field of genetics study?

Inherited traits and their variation.

Which molecule makes up genes?

Deoxyribonucleic acid (DNA).

Traits result from an interaction between and .

genes; the environment

Name the three chemical components of a DNA nucleotide.

Phosphate, deoxyribose sugar, nitrogenous base.

Which bases pair in DNA?

Adenine–Thymine and Guanine–Cytosine.

List the four components of an RNA nucleotide.

Phosphate, ribose sugar, adenine, guanine, cytosine, or uracil (uracil replaces thymine).

How does RNA differ structurally from DNA?

RNA is single-stranded, contains ribose, and uses uracil instead of thymine.

What are alleles?

Variant forms of the same gene.

Mutations that occur in sperm or egg cells are called and are to the next generation.

germline mutations; heritable

How many chromosomes are found in a human somatic cell, and how are they categorized?

46 chromosomes: 22 pairs of autosomes and 1 pair of sex chromosomes.

What is a karyotype?

A chart displaying an individual's chromosome pairs from largest to smallest.

Define the human genome.

The complete set of genetic information, including all genes and non-coding DNA, in a human cell.

Somatic cells are (ploidy level), whereas sperm and egg cells are .

diploid; haploid

What dual property makes stem cells unique?

They can self-renew and differentiate into specialized cell types.

State the basic difference between prokaryotic and eukaryotic cells concerning the nucleus.

Prokaryotes lack a membrane-bound nucleus; eukaryotes possess one.

What is the primary function of the plasma membrane?

To act as a selective barrier regulating entry and exit of substances.

Which organelle houses DNA and directs cellular activities?

The nucleus.

State the main function of rough endoplasmic reticulum.

Protein synthesis and initial folding (via ribosomes on its surface).

Give two functions of smooth endoplasmic reticulum.

Lipid synthesis and detoxification of drugs/poisons.

Describe the key role of the Golgi apparatus.

Modifies, sorts, and packages proteins and lipids for secretion or delivery.

Which organelle contains hydrolytic enzymes for intracellular digestion?

Lysosome.

What do peroxisomes do?

Break down lipids and detoxify harmful substances, producing hydrogen peroxide.

Which organelle is the main site of ATP production?

Mitochondrion.

What is the function of ribosomes?

Translation of mRNA into polypeptide chains (protein synthesis).

List three structural proteins that make up the cytoskeleton.

Microtubules, microfilaments, intermediate filaments.

Image quality in light microscopy relies on which three parameters?

Magnification, resolution, and contrast.

About how many times can a light microscope magnify effectively?

Up to ~1,000× the actual specimen size.

Give two common forensic uses of DNA profiling.

Identifying crime suspects and identifying victims of disasters.

List two key differences between single-gene diseases and multifactorial diseases.

Single-gene diseases allow predictable inheritance patterns and potential presymptomatic testing; multifactorial diseases involve multiple genes and environmental factors, making prediction harder.

Define a Mendelian trait.

A trait determined primarily by a single gene, following Mendel’s laws.

What characterizes a multifactorial trait?

It is influenced by one or more genes plus environmental factors.

Differentiate genotype and phenotype.

Genotype is the allele combination an individual carries; phenotype is the observable trait or expression.

When is a dominant allele expressed?

When at least one copy is present.

What does a pedigree allow geneticists to do?

Trace inheritance patterns of traits across generations.

What is the role of telomeres?

Protect chromosome ends; their shortening limits the number of cell divisions.

Apoptosis begins when a cell receives what kind of signal?

A 'death signal' that activates caspase enzymes.

Name the four main phases of the eukaryotic cell cycle in order.

G1, S, G2, M.

Interphase occupies roughly what percentage of the cell cycle?

About 90%.

What is the purpose of cell-cycle checkpoints?

To ensure events occur in proper sequence and prevent damaged cells from dividing.

State one major event that occurs during prophase of mitosis.

Chromosomes condense and the mitotic spindle begins to form.

What key alignment defines metaphase?

Chromosomes line up along the cell’s equatorial metaphase plate.

Which event characterizes anaphase?

Sister chromatids separate and move toward opposite poles.

List two notable events of telophase.

Chromosomes decondense and nuclear envelopes reform around each set.

How does cytokinesis typically occur in animal cells?

By formation of a cleavage furrow produced by a contractile ring of microfilaments.

How does cytokinesis differ in plant cells?

A cell plate forms from vesicles, ultimately creating a new cell wall.

What is the role of centrosomes in mitosis?

They organize the spindle microtubules that separate chromosomes.

Differentiate kinetochore microtubules from non-kinetochore microtubules.

Kinetochore microtubules attach to chromosomes; non-kinetochore microtubules overlap and push to elongate the cell.

What two protein families form the core of the cell-cycle clock?

Cyclins and cyclin-dependent kinases (Cdks).

MPF, a cyclin-Cdk complex, allows a cell to pass which checkpoint?

The G2 checkpoint into mitosis.

Why is the G1 checkpoint often considered the cell-cycle 'restriction point'?

Because passing it commits the cell to DNA replication and division; failure to pass sends the cell to G0.

How does paracrine signaling differ from endocrine signaling?

Paracrine targets nearby cells; endocrine targets distant cells via the bloodstream.

In a phospholipid bilayer, which region is hydrophilic and which is hydrophobic?

The phosphate 'head' is hydrophilic; fatty-acid 'tails' are hydrophobic.

Name any four of the six major functions of membrane proteins.

Transport, enzymatic activity, signal transduction, cell-cell recognition, intercellular joining, attachment to cytoskeleton/ECM.

What symptom can sodium-channel mutations cause?

Extreme pain insensitivity or the opposite—chronic pain.

Cystic fibrosis results from mutations in which type of ion channel?

Chloride channel (CFTR gene).

Define genomics.

The study and comparison of entire genomes of organisms.

What is metagenomics?

Sequencing and analyzing all DNA present in an environmental sample to study entire microbial communities.

During which cell-cycle phase are chromosomes replicated?

S phase.

What causes a benign tumor to become malignant?

Ability to invade surrounding tissues and metastasize to distant sites.

Binary fission is the cell-division mechanism in which organisms?

Prokaryotes such as bacteria and archaea.

Which enzyme prevents telomere shortening in germline and cancer cells?

Telomerase.

Name the proteases activated during apoptosis.

Caspases.

What is pharmacogenomics?

The study of how genetic variation affects individual responses to drugs.

State one application of DNA testing in historical studies.

Confirming that Thomas Jefferson fathered children with Sally Hemmings.

Which type of microscopy uses fluorescent tags to visualize structures?

Fluorescence microscopy.

Why are lysosomes important in defense against oral pathogens?

They digest engulfed bacteria and debris, aiding immune responses in periodontal tissues.

What dental condition can arise from defective Golgi trafficking in ameloblasts?

Amelogenesis imperfecta (weak or improperly formed enamel).

Name two macromolecule classes that provide energy storage or structural support.

Carbohydrates and lipids.

Which bacterial species is most commonly associated with dental caries?

Streptococcus mutans.

What is osseointegration in implant dentistry?

Bone cells adhering to and growing around a titanium implant surface.

How do fibroblasts aid periodontal ligament repair?

They synthesize collagen to rebuild connective tissue fibers.

Which cellular process is up-regulated during healing after tooth extraction?

Mitosis for rapid replacement of damaged oral tissues.

Which organelle imbalance may contribute to periodontal disease inflammation?

Mitochondrial dysfunction leading to excess reactive oxygen species.