Cell Biology
What is the function of the cytoplasm?
Provides a location where chemical reactions can take place to maintain homeostasis.
>> Other possibilities…
Holds components of the cell (organization, protection of organelles); maintains cell shape and structure; provides a medium for the transport and storage of macromolecules; removes waste materials
DNA is typically found as a single strand. T/F?
False – DNA is typically found as two polynucleotide chains twisted together (double helix conformation)
What is the gene ‘start’ site called?
Promoter (Transcription: Initiation)
What is a carcinogen?
Any substance that increases the likelihood of cancer
What is meant by ‘morphology’?
This refers to the form of a living organism – it can be used to distinguish cells from one another (what makes cells different – overall structure, physical characteristics)
RNA can only be found as a single polynucleotide chain. T/F?
False – RNA can be found in various conformations! This is especially true for viruses – pseudoknot conformations are common for Zika Virus (ZIKV), and Human Immunodeficiency Virus (HIV) contains RNA with double-helical character.
What is the sequence of DNA that signals RNA polymerase to stop transcription?
Terminator (Transcription: Termination)
What are three ways we can prevent cancer?
Use sunscreen (minimizes risk of skin cancer); maintain healthy exercise and diet practices (minimizes risk of stomach and colon cancer); stay on top of routine screenings (aids in the early detection of breast, cervical, prostate and blood cancers)
Name two key features of the plasma membrane.
1) It is a phospholipid bilayer; 2) functions as a selectively permeable barrier (to keep molecules in/out)
>> Other possibilities…
Consists of proteins, carbohydrates; connection for the cytoskeleton to the extracellular matrix; function – maintains overall cell structure (keeps cell in place)
How many nucleotides are in one codon, and what does this generate?
1) 3; 2) An amino acid
Explain dominant and recessive traits.
A dominant trait will overpower the recessive one; these are represented by capital and lowercase letters, respectively. The recessive trait will only be genetically expressed in the offspring when inherited from both parents – in other words, when it is not ‘masked’ by a dominant characteristic.
What are the two genetic mutations leading to cancer?
Loss of tumor suppressor genes, gain of oncogenes
What are the four main types of cells that form tissue?
1) Epithelial cells – tightly attached to one another and cover the interior of hollow organs (blood vessels) or form the surface of things (skin); 2) Nerve cells – specialized for communication like sending signals from the brain to muscles; 3) Muscle cells – specialized for movement like contraction (heart, digestive organs); 4) Connective tissue cells – provide structural strength to the body, defend against foreign invaders
Name two features that make DNA and RNA different from one another.
1) The sugar component of a DNA nucleotide contains only two oxygens – the hydroxyl group at the 2’ position of its sugar molecule has been reduced; 2) RNA strands have the base uracil (U) in place of thymine (T).
>> Other possibilities…
> DNA: found as two polynucleotide chains, strands are antiparallel, needed as a template for its own replication;
> RNA: usually found as a single polynucleotide chain, not the primary genetic material (not used as a template for self-replication)
Who is credited as the founder of evolutionary genetics? And what was the observation and hypothesis made that established the concept of evolution?
1) Charles Darwin; 2) Observation: characteristics of many animals vary greatly among the different environments; Hypothesis: separate species may have arisen from an original ancestor
What are three approaches to fighting cancer? Briefly explain.
Surgery: removal of the primary tumor – can be a cure but more commonly needs to be coupled with another form of therapy; Radiotherapy: radiation at the site of cancer – while high doses of x- or gamma-rays kills cancer cells, it also introduces mutations in the DNA of healthy cells which increases the risk of cancer development; Chemotherapy: use of chemicals to kill cancer cells – systemic (whole body) treatment that can cause cells (both healthy, malignant) to die by disrupting cell division/growth
Cells can have different proportions of organelles. Give two examples – name the type of cell, what role this feature has in cell function.
1) Muscle cells contain large numbers of mitochondria to meet the high energy demands (provide more energy, ATP); 2) Certain bacteria – like E. coli – contain flagella, structures densely packed with cytoskeletal components, to aid in cell motility (‘swimming’)
>> Other possibilities…
Phagocytic white blood cells consume and breakdown an abundance of foreign material which requires large numbers of lysosomes; macrophage foam cells contain more lipid droplets as a result of their efforts to control cholesterol levels; plant cells have chloroplasts that are responsible for converting sunlight into energy (photosynthesis)
What does the third tier in the structural hierarchy of proteins describe?
3D shape
Describe natural selection and provide an example.
Over time, natural selection results in changes in inherited characteristics of a population which increase a species fitness in its environment. For example, a population of giraffes originally contains animals with varying neck lengths. However, their habitat only has trees that are very tall. As a result, giraffes with shorter necks gradually die off because they cannot reach the leaves (main food source). Hence, the genetic trait of a long neck is ‘selected for’ to aid in species survival.
Describe immunotherapy – define, give three key features.
Immunotherapy is a modern approach to cancer treatment that is based on engineering our own cells to fight cancer cells. Three features: personalized for each individual and cancer; immune cells can recognize cancer cells by the expression of proteins that are unique to that cancer; strengthen immune cells through genetic engineering