Cell Biology Review

These flashcards cover essential concepts in cell biology, genetics, microbiology, and ecology to help students prepare for their exam.

What are the differences between eukaryotic and prokaryotic cells?

Prokaryotic cells are smaller, do not contain membrane-bound organelles, and lack a nucleus; eukaryotic cells contain these structures.

How is genetic information stored in a prokaryotic cell?

Genetic information is found free within the cytoplasm as chromosomal DNA (single large loop of circular DNA) and plasmid DNA.

What are plasmids?

Small, circular loops of DNA found free in the cytoplasm that carry genes providing genetic advantages, such as antibiotic resistance.

What is the difference in order of magnitude between a human hair (100 µm) and the HIV virus (100 nm)?

The difference is 3 orders of magnitude.

What is the order of magnitude calculation between a human hair and the HIV virus?

100 µm = 10^-4 m; 100 nm = 10^-7 m, difference: -4 - (-7) = 3.

List the components of both plant and animal cells.

Nucleus, cytoplasm, cell membrane, mitochondria, ribosomes.

Describe the structure of the cytoplasm.

The cytoplasm is a fluid component of the cell that contains organelles, enzymes, and dissolved ions and nutrients.

What is the function of the cell membrane?

It controls the entry and exit of materials into and out of the cell.

What is the function of the mitochondria?

The mitochondria are the site of later stages of aerobic respiration where ATP is produced.

What is the function of the ribosomes?

Ribosomes join amino acids in a specific order during translation for protein synthesis.

What is the function of the plant cell wall?

The plant cell wall provides strength and prevents the cell from bursting when water enters by osmosis.

Describe how sperm cells in animals are adapted to their function.

Sperm cells have a haploid nucleus, a tail for movement, mitochondria for energy, and an acrosome with enzymes for digesting the egg cell membrane.

Describe how nerve cells in animals are adapted to their function.

Nerve cells have a long axon for transmitting impulses, dendrites for receiving impulses, and a myelin sheath that speeds up impulse transmission.

Describe how muscle cells are adapted to their function.

Muscle cells have protein filaments for contraction, mitochondria for energy, and merged cells in skeletal muscle for simultaneous contraction.

Describe how root hair cells in plants are adapted to their function.

Root hair cells have a large surface area for nutrient and water absorption and thin walls to facilitate water absorption.

Describe how xylem cells in plants are adapted to their function.

Xylem cells have no upper or lower margins between cells for continuous water flow and thick side walls for strength.

Describe how phloem cells in plants are adapted to their function.

Phloem cells have sieve plates for transporting solutions and companion cells for energy needed in active transport.

Why is cell differentiation important?

Cell differentiation allows for the production of different tissues and organs that perform various vital functions in the body.

What changes does a cell go through as it differentiates?

A cell becomes specialized through the acquisition of different sub-cellular structures for a specific function.

Define magnification.

Magnification is the number of times larger an image appears compared to the actual size of the object.

How does a light microscope work?

A light microscope passes a beam of light through a specimen, allowing it to be observed through the eyepiece lens.

What are the advantages of light microscopes?

Inexpensive, easy to use, portable, and can observe both dead and living specimens.

How does an electron microscope work?

An electron microscope uses a beam of electrons focused by magnets, hitting a fluorescent screen to produce an image.

Why do electron microscopes have greater magnification and resolution?

They use a beam of electrons with a shorter wavelength than light photons.

How have electron microscopes advanced our understanding of cells?

They allow observation of small sub-cellular structures in detail and provide accurate explanations about cell structure and function.

What are the disadvantages of electron microscopes?

Expensive, large and less portable, require training, and can only observe dead specimens.

How can the magnification of an image be calculated?

Magnification = size of image / size of real object.

What is standard form?

Standard form expresses numbers as a figure between 1 and 10 multiplied by a power of 10.

How often do bacteria multiply?

Bacteria multiply once every 20 minutes if nutrients and temperature are adequate.

State two ways bacteria can be grown.

In a nutrient broth solution or on agar gel plates.

What nutrients are in a nutrient broth solution?

Nitrogen for protein synthesis, carbohydrates for energy, and other minerals.

How is an uncontaminated culture prepared using aseptic technique?

Sterilize dishes and agar, streak with inoculating loop, secure dish, and incubate at 25°C.

Why must inoculating loops be sterilized?

To kill any bacteria present on the loop.

Why must the Petri dish lid be secured with tape?

To prevent contamination while allowing oxygen for aerobic bacteria.

Why are cultures incubated at 25°C in school laboratories?

To prevent the growth of harmful pathogens.

What is the formula to calculate the cross-sectional area of a bacterial colony?

πr², where r = radius (diameter/2).

How is the number of bacteria in a population calculated from mean division time?

Calculate the number of divisions and use the formula: final count = initial count x 2^number of divisions.

Calculate the number of bacteria after 3 hours that divides every 15 minutes with 5 present now.

After 12 divisions, the count is 20480 or 2.048 x 10^4.

What is the diameter used for calculating the area of a bacterial colony?

The diameter is used to find the radius by dividing by 2.

What is the significance of plasmids in bacteria?

They carry genes that can provide advantages like antibiotic resistance.

How does the structure of mitochondria relate to its function?

Mitochondria have a double membrane and a large surface area for ATP production.

What is the role of the acrosome in sperm cells?

Contains enzymes that help digest the egg cell membrane.

What is myelin sheath and its function in nerve cells?

An insulating layer that speeds up electrical impulse transmission.

What is the function of the companion cells in phloem?

They provide energy needed for active transport of substances in the phloem.

How does the arrangement of filaments in muscle cells assist their function?

It allows sliding contractions, enabling muscle movement.

How does a healthy diet contribute to cell function?

Provides necessary nutrients for cell growth, energy, and repair.

What is aerobic respiration?

A process that uses oxygen to produce energy (ATP) from glucose.

What is the significance of ATP in cellular processes?

ATP acts as the energy currency for cellular activities.

What are the two types of cell division?

Mitosis and meiosis.

What is the result of meiosis?

Four genetically diverse haploid cells (gametes).

What are the phases of mitosis?

Prophase, metaphase, anaphase, and telophase.

How do stem cells differ from specialized cells?

Stem cells can differentiate into many cell types, while specialized cells have a defined role.

What is the function of the cell nucleus?

It stores genetic material and controls cell activities.

What is osmosis?

The movement of water across a semipermeable membrane from an area of lower solute concentration to higher solute concentration.

What are the main functions of proteins in cells?

They are involved in structural support, enzymes, transport, and signaling.

How does the structure of plant cell walls affect their function?

Cell walls provide rigidity and support, maintaining cell shape.

What is the primary role of chloroplasts in plant cells?

To conduct photosynthesis and produce glucose.

How do vacuoles contribute to plant cell structure?

They store substances and maintain turgor pressure against the cell wall.

What role do enzymes play in biological reactions?

They speed up chemical reactions by lowering the activation energy.

Why is it important to use a sterile technique in microbiology?

To avoid contamination and ensure accurate results in experiments.

What is the difference between simple and facilitated diffusion?

Simple diffusion is passive movement of molecules, while facilitated diffusion uses transport proteins.

What is the role of the rough endoplasmic reticulum?

It synthesizes proteins and is studded with ribosomes.

What is the significance of the golgi apparatus?

It modifies, sorts, and packages proteins and lipids for transport.

What is the function of lysosomes?

They contain enzymes that break down waste material and cellular debris.

Describe the fluid mosaic model of the cell membrane.

It depicts the membrane as a flexible layer composed of lipid molecules with proteins floating within it.

What are fatty acids and their role in cell membranes?

Fatty acids are components of phospholipids that make up cell membranes, affecting membrane fluidity.

What is the role of glucose in respiration?

Glucose is the primary fuel for cellular respiration to produce ATP.

What are the stages of cellular respiration?

Glycolysis, Krebs cycle, and electron transport chain.

What is the main purpose of the Krebs cycle?

To produce electron carriers that are used in the electron transport chain to generate ATP.

What is anaerobic respiration?

Respiration that occurs without oxygen, producing less energy and often resulting in lactic acid or ethanol.

In what type of organisms does fermentation usually occur?

It typically occurs in yeast and some bacteria.

What are the products of alcoholic fermentation?

Ethanol and carbon dioxide.

What ecological role do bacteria play?

Bacteria decompose organic matter and recycle nutrients in ecosystems.

How does antibiotic resistance occur in bacteria?

When bacteria mutate or acquire genes enabling them to survive antibiotic treatment.

What is the basic structure of a virus?

Viruses consist of genetic material (DNA or RNA) surrounded by a protein coat.

What type of cells are viruses incapable of infecting?

Viruses cannot infect prokaryotic cells.

What is the cycle of viral infection?

Attachment, penetration, replication, assembly, and release.

How do vaccines work?

Vaccines stimulate the immune system to recognize and fight pathogens without causing disease.

What is herd immunity?

When a large portion of a population becomes immune to a disease, providing indirect protection to unvaccinated individuals.

What factors can influence cell signaling?

Chemical signals, receptor presence, and the environment can affect how cells communicate.

How does apoptosis contribute to homeostasis?

Apoptosis removes damaged or unnecessary cells, maintaining balance in the body.

What role do hormones play in the body?

Hormones act as chemical messengers that regulate physiological processes.

What is a feedback loop?

A biological mechanism that regulates systems within organisms, often maintaining homeostasis.

What does the term 'homeostasis' mean?

The maintenance of stable internal conditions despite external changes.

How do neurotransmitters function?

They transmit signals across a synapse from one neuron to another.

What is the role of the endocrine system?

The endocrine system regulates bodily functions through hormones.

How do muscle contractions occur at the cellular level?

Muscle contractions occur through the sliding filament model, where actin and myosin filaments slide over each other.

What is the significance of carbon in biological molecules?

Carbon is essential for forming the backbone of organic molecules in living organisms.

What are the four main macromolecules?

Carbohydrates, lipids, proteins, and nucleic acids.

How do anti-inflammatory drugs work?

They inhibit enzymes involved in the inflammatory response.

What is the purpose of gene therapy?

To treat or prevent disease by altering genes within an individual's cells.

Define microbiome.

The collection of microorganisms living in a particular environment, especially the body.

How can environmental factors influence gene expression?

Environmental conditions can activate or deactivate genes affecting development or disease.

What is symbiosis?

A close ecological relationship between two different species.

How do primary and secondary succession differ?

Primary succession occurs in lifeless areas, while secondary succession follows disturbances in areas with soil.

What are the roles of keystone species in ecosystems?

Keystone species have a disproportionate effect on their environment relative to their abundance.

What are trophic levels?

The different levels in a food chain or food web, indicating the flow of energy through an ecosystem.

How does energy transfer within an ecosystem?

Energy flows from producers to consumers and then to decomposers.

What is biomagnification?

The increasing concentration of toxic substances in organisms at each trophic level.

What is the significance of biodiversity?

Biodiversity contributes to ecosystem resilience, stability, and productivity.