Biology Chapter 11 Flashcards
Describe the evidence that suggests that cigarette smoking causes lung cancer.
In human lung cells growing in a lab, a component of tobacco smoke, BPDE, bound to DNA within a gene called p53, which codes for a protein that normally helps suppress the formation of tumors.
Explain how the many types of adult human cells are formed.
The variance in types of cells in humans might be a result of gene expression:
- a gene is turned on and transcribed into RNA and
- information flows from
- genes to proteins and
- genotype to phenotype.
Explain how the lac operon works.
- The lac operon uses
- a promoter, a control sequence where the transcription enzyme attaches and initiates transcription,
- an operator, a DNA segment that acts as a switch that is turned on or off, and
- a repressor, which binds to the operator and physically blocks the attachment of RNA polymerase and transcription.
Explain how DNA packing influences gene expression.
- DNA packing occurs in female mammals
- One of the two x chromosomes is inactivated at random
- If a female is heterozygous for a gene on the X chromosome,
- about half her cells will express one allele and
- the others will express the alternate allele.
Explain how RNA is processed in eukaryotes before it leaves the nucleus. Explain how this processing can result in different proteins from the same gene.
The eukaryotic cell
- localizes transcription in the nucleus and
- processes RNA in the nucleus.
- RNA processing includes the
- addition of a cap and tail to the RNA,
- removal of any introns, and
- splicing together of the remaining exons.
Describe the mechanisms used to regulate gene expression after eukaryotic mRNA is transported to the cytoplasm.
- Unpacking of DNA
- Transcription
- Processing of RNA
- Breakdown of mRNA
- Translation of mRNA
- Various Changes to polypeptide
- Breakdown of protein
Describe the significance of cell signaling in multicellular organisms.
Cell signaling allows cells to regulate genes in other cells of the body by producing chemicals like hormones
Explain how homeotic genes help us understand animal evolution and development.
Homeotic genes are the “master control genes”. When there is a homeotic gene mutation, it can produce strange effects, because the homeotic genes are responsible for deciding which body parts will grow where. This can lead to huge evolutionary changes.
Explain how DNA microarrays help scientists visualize gene expression.
microarrays cause active genes to glow, helping scientists understand which genes affect different parts of expression
Explain how every cell has the potential to act like every other cell. Illustrate with examples.
Each cell contains a complete genome, and it becomes the specialized cell through expression, depending on what the body needs.
An example of this is cloning. The first sheep was cloned by replacing the nucleus of a sheep egg cell with the nucleus of that sheep’s adult cell, which became an entire, genetically identical organism.
Explain how plants are cloned, what this reveals about cell differentiation, and why growers clone plants.
Plants are cloned by taking a small cutting of one plant and placing it in a special liquid which allows it to take root and grow again into a genetically identical plant. Growers do this to ensure that they are going to get exactly the traits they desire.
Compare the properties of embryonic and adult stem cells. Explain why embryonic stem cells may be better to produce replacement tissues in adults.
The advantage over embryonic stem cells compared to adult stem cells is that adult stem cells have already begun the process of differentiation, and are thus limited in what they can become, while embryonic stem cells can become any cell the body needs.
Explain how mutations in proto-oncogenes and tumor suppressor genes can lead to cancer.
Mutations make proto-oncogenes and tumor suppressor genes become oncogenes, which cause cancer.
Explain how a population of cancer cells survives
Cancer cells experience rapid evolution. THey tend to reproduce more than the host organ can support, and produce differentiated offspring, These offspring may be better suited to live on a different gene, which means they will pass that trait on.
