Biology 1-5 Flashcards
What are the four fundamental tenets of the cell theory?
- All living things are made of cells.
- The cell is the basic functional unit of life.
- All cells arise from other cells.
- Genetic information is carried in the form of DNA and is passed from parent to daughter cell.
Describe the functions of the following:
1. Nucleus
2. Mitochondrion
- Nucleus stores genetic information and is the site of transcription.
- Mitochondria is involved in ATP production and apoptosis.
Describe the functions of the following:
3. Lysosome
4. Rough endoplasmic reticulum
- Lysosomes break down cellular waste products and molecules through endocytosis, and can also be involved in apoptosis.
- The rough endoplasmic reticulum synthesizes proteins destined for secretion.
Describe the functions of the following:
5. Smooth endoplasmic reticulum
6. Golgi Apparatus
7. Peroxisome
- Smooth ER is involved in lipid synthesis and detoxification.
- Golgi apparatus packages, modifies, and distributes cellular products.
- Peroxisomes break down very long chain fatty acids, synthesize lipids, and contribute to the pentose phosphate pathway.
A child is diagnosed with an enzyme deficiency that prevents the production of hydrogen peroxide. What would the likely outcome be of such a deficiency?
Peroxisomes are dependent on hydrogen peroxide for their functions, so an enzyme deficiency that results in an inability to form hydrogen peroxide would likely result in an inability to digest very long chain fatty acids.
These fatty chains would build up in peroxisomes until they displaced cellular contents, ultimately resulting in cell death?
What are the predominant proteins in each cytoskeletal element?
1. Microfilaments.
2. Microtubules
3. Intermediate filaments.
- Microfilaments are composed of actin.
- Microtubules are composes of tubulin.
- Intermediate filaments differ by cell type but may be composed of keratin, desmin, vimentin, and lamins.
How do the cytoskeletal structure of centrioles and flagella differ?
Centrioles consist of nine triplets of microtubules around a hollow center.
Flagella consist of nine doublets on the outside, with two microtubules on the inside.
Classify the following as epithelial cells or connective tissues:
1. Fibroblasts - produce collagen in a number of organs.
2. Endothelial cells - line blood vessels.
3. a-cells - produce glucagon in the pancreas
4. Osteoblasts - produce osteoid, material that hardens into bones.
5. Chondroblasts - produce cartilage.
- Connective tissue cells.
- Epithelial cells.
- Epithelial cells.
- Connective tissue cells.
- Connective tissue cells.
In what ways are archaea similar to bacteria?
Both are single celled-organisms that lack a nucleus or membrane-bound organelles, contain a single circular chromosome, and divide by binary fission or budding.
In what ways are Archaea similar to eukaryotes?
They start translation with methionine, contain similar RNA polymerases, and contain DNA associated with histones.
What are the three common shapes of bacteria?
spherical (cocci)
Rod-shaped (bacilli)
Spiral-shaped (spirilli)
Describe obligate aerobe
Can survive in the presence of oxygen and can carry out aerobic metabolism.
Cannot survive if oxygen is absent and cannot carry of anaerobic metabolism.
Describe facultative anaerobe
Can survive in the presence of oxygen and can carry out aerobic metabolism.
Can also survive is oxygen is absent and can carry out anaerobic metabolism.
Describe obligate anaerobe
Cannot survive in the presence of oxygen or carry out aerobic metabolism.
Can survive when oxygen is absent and can carry out anaerobic metabolism.
Describe aerotolerant anaerobe
Can survive in the presence of oxygen but cannot carry out aerobic metabolism.
Can survive in the absence of oxygen and can carry out anaerobic metabolism.
What difference between the envelopes of gram-positive and gram-negative bacteria make gram-positive bacteria more susceptible to antibiotics such as penicillin.
The antibiotic penicillin targets the enzyme that catalyzes the cross linking of peptidoglycan.
Gram-positive bacteria have a thick layer of peptidoglycan and lipoteichoic acid, and contain no outer membrane.
Gram negative bacteria only have a thin layer of peptidoglycan but also have an outer membrane containing lipopolysaccharides and phospholipids.
Penicillin and antibiotics with similar function can more easily reach and weaken the peptidoglycan layer of gram positive bacteria.
How do the structure of eukaryotic and prokaryotic flagella differ?
Eukaryotic flagella contain microtubules composed of tubulin, organized in a 9+2 arrangement. Bacterial flagella are made of flagellin and consist of a filament, a basal body, and a hook.
Describe the transformation mechanism of bacterial genetic recombination.
Transformation - the acquisition of exogenous genetic material that can be integrated into the bacterial genome.
Describe the conjugation mechanism of bacterial genetic recombination.
Conjugation - transfer of genetic material from one bacterium to another across a conjugation bridge.
A plasmid can be transferred from F+ cells to F- cells, or a portion of the genome can be transferred from an Hfr cell to a recipient.
Describe the transduction mechanism of bacterial genetic recombination.
Transduction - transfer of genetic material from one bacterium to another by a bacteriophage.
What are the four phases of the bacterial growth curve and what are the features of each phase?
Lag phase - Bacteria get used to the environment; little growth.
Exponential phase - Bacteria use available resources to multiply at an exponential rate.
Stationary phase - Bacterial multiplication shows as resources are used up.
Death phase - Bacteria die as resources become insufficient to support the colony.
Why are viruses considered obligate intracellular parasites?
Viruses do not contain organelles such as ribosomes; therefore, in order to reproduce and synthesize proteins, virus must infect cells and hijack their machinery.
A coronavirus, which causes the common cold, is described as an enveloped, single-stranded positive-sense RNA virus. What does this indicate about the virus?
The description indicates that the virus contains an outer layer of phospholipids with an inner capsid. Within the capsid, there is a single stranded RNA that can be immediately translated to protein by the ribosomes of the host cell.
Briefly describe the pathway of retroviral nucleic acids from infection of a host cell to release of viral progeny.
Nucleus enters as single-stranded RNA, which undergoes reverse transcription (using reverse transcriptase) to form the double stranded DNA. DNA enters host genome and replicates with the host cell. DNA is transcribed to mRNA, which can be used to make structural proteins. mRNA doubles as the viral genome for new virions. Once new virions are assembled from the structural proteins and mRNA, virions released to infect other cells.
What are the difference between the lytic and lysogenic cycles?
Lytic cycle - bacteriophages replicate in host cell in extremely high numbers until host cell lyses and released virions.
Lysogenic cycle - bacteriophage genome enters host genome and replicates with host cell as provirus. In response to appropriate stimulus, provirus may leave host genome and can be used to synthesize new virions.
How do prions cause disease?
Prions cause disease by triggering a change in the conformation of a protein from an alpha helix to a beta pleated sheet. Change reduces solubility of the protein and makes it highly resistant degradation.
What are the fives stages of the cell cycle and what happens in each stage?
G1 - cell grows and performs its normal functions. DNA is examined and repaired.
S - DNA is replicated.
G2 - cell continues to grow and replicates organelles in preparation for mitosis. Cell continues to perform its normal functions.
M - Mitosis (cell division) occurs.
G0 - The cell performs its normal functions and is NOT preparing to divide.
What are the four phases of mitosis and what happens in each phase?
Prophase - Chromosomes condense, nuclear membrane dissolves, nucleoli disappear, centrioles migrate to opposite poles and begin forming the spindle apparatus.
Metaphase - chromosomes gather along the metaphase plate in the center of the cell under the guidance of the spindle apparatus.
Anaphase - Sister chromatids separate, and a copy of each chromosome migrates to the opposite pole.
Telophase and Cytokinesis - Chromosomes decondense, nuclear membrane reforms, nucleoli reappear, spindle apparatus breaks down, cell divides into two identical daughter cells.
What is the number and ploidy of the daughter cells produced from meiosis 1?
After meiosis 1, there are two haploid daughter cells.
What is the number and ploidy of daughter cells produced from meiosis 2?
After meiosis 2, there are up to four haploid gametes.
What is the difference between homologous chromosomes and sister chromatids?
Homologous chromosomes are related chromosomes of opposite parental origin (such as maternal chromosome 15 and paternal chromosome 15)
Sister chromatids are identical copies of the same DNA that are held together at the centromere. After S phase, a cell contains 92 chromatids, 46 chromosomes, and 23 homologous pairs.
What are the differences from the analogous phases between Meiotic Phase and Mitotic Phase?
1. Prophase 1
2. Metaphase 1
3. Anaphase 1
4. Telophase 1
Differences from Mitotic Phase
Prophase 1 - homologous chromosomes come together as tetrads during synapsis; crossing over.
Metaphase 1 - Homologous chromosomes line up on opposite sides of the metaphase plate, rather than individual chromosomes lining up on the metaphase plate.
Anaphase 1 - Homologous chromosomes separate from each other; centromeres do not break.
Telophase 1 - Chromatin may or may not decondense; interkinesis occurs as the cell prepares for meiosis 2.
What are the functions of interstitial cells of Leydig and Sertoli cells?
Interstitial cells of Leydig secrete testosterone and other male sex hormones (androgens). Sertoli cells nourish sperm during their development.
