Untitled Flashcards Set

1. Describe three similarities and three differences between plants and animals in meiosis. 

Three similarities: 

• Both animals and plants utilize independent assortment and crossing over to generate genetic diversity in daughter cells.  

• Both animals and plants reduce the chromosomes in half, from diploid to haploid. 

• Both animals and plants experience crossing over during ProphaseI, exchanging genetic material between homologous chromosomes. 

Three differences: 

• In animals, the cell membrane is pinched to divide, whereas in plants, a new cell wall is built between the daughter cells 

• In animals, gametes are produced directly through meiosis, whereas plants produce spores that develop into a gamete-producing generation. 

• In animals, centrioles organize spindle fibers, whereas plants form spindles without centrioles. 

How can we use the similarities in plant and animal meiosis to create seedless/sterile offspring? 

• We can use the similarities in plant and animal meiosis to create seedless/sterile offspring by intentionally disrupting the shared mechanisms by adding extra chromosomes or creating incompatible hybrids to prevent the formation of viable gametes or spores, leading to seedless fruits or sterility. 

What are the pros and cons of creating seedless/sterile agriculture plants/animals? 

Plants:

• Pros: 

• Creating sterile plants reduces the chances of spreading invasive plants around where they are not native and choking out local flora. 

• Seedless plants are more appealing for consumption 

• Seedless plants have a more extended shelf life 

• Cons: 

• Plants lose the ability to reproduce naturally 

• Creating seedless varieties may require advanced techniques 

• Relying on few sterile varieties makes our food supply vulnerable to outbreaks of diseases and pests 

Animals: 

• Pros: 

• Sterile animals exhibit faster growth rates and better meat quality 

• Reduces pest populations by minimizing pesticide use 

• It helps to limit the spread of some animal diseases 

• Cons: 

• Concerns about animal welfare 

• Potential environmental risks of releasing sterile animals into the environment 

• It can have unforeseen effects on the food chain or other ecological processes. 

2. Explain the two sources of genetic variation in meiosis AND why mitosis does not produce variation. 

• The two sources of genetic variation in meiosis are independent assortment of chromosomes and crossing over. 

• Mitosis does not produce variation because chromosomes are duplicated and then precisely separated during mitosis, ensuring that each daughter cell receives an identical set of chromosomes. Therefore, the way chromosomes are handled, there is no chance for variation to occur. 

DRAW an image to illustrate using an example showing at what stage these sources of genetic variation occur. 

Calculate the possible combinations of potential gametes in an animal with a diploid count of twelve (2n = 12). 

• Find the haploid number (n): 

• If 2n = 12, then n = 12 / 2 = 6 

• Calculate the possible gamete combinations: 

• Possible combinations = 2^n = 2^6 = 64 

3. Explain the relationship between cancer and the cell cycle. 

• The relationship between cancer and the cell cycle is that disruptions in the cell cycle lead to uncontrolled cell division, which causes cancer. 

How do disruptions in the cell cycle lead to cancer, and what are the specific changes that occur in the regulation of the cell cycle during cancer development? 

• Disruptions in the cell cycle lead to cancer. Cancer arises when cells lose the ability to regulate their growth and division, often due to mutations in genes that control the cell cycle. Disruptions in the cell cycle allow cells with damaged DNA to divide uncontrollably due to the loss of checkpoint control, overactive growth signals from oncogenes, and the inactivation of tumor suppressor genes. 

• The specific changes that occur in the cell cycle regulation during cancer development are increased cyclin/CDK activity, mutations in checkpoint proteins, telomerase activation, and ignoring growth inhibitory signals. 

How does human cancer compare to prokaryote cell division? 

• Human cancer is compared to prokaryote cell division by increasing cell division, which involves the replication of DNA. 

4. Describe the cell cycle in as much detail as you can recall, including its different phases, the key events that occur during each phase, and how the cell ensures proper division. 

• Cell Cycle: 

• G1: The cell grows 

• G0: Cells may enter G0, a non-dividing phase 

• G1/S checkpoint: After the G1/S checkpoint, the cell is committed to dividing 

• S: In S, DNA duplicates 

• Interphase: cell growth 

• G2: the cell prepares for mitosis

• G2/M checkpoint: After the G2/M checkpoint, the cell can divide 

• M phase: nuclear and cell division; Mitosis and cytokinesis (cell division) take place in M phase 

• Spindle assembly checkpoint  

• Cytokinesis 

• The cell ensures proper division by several checkpoints such as G1, G2, and the spindle assembly checkpoint.

Additionally, explain the role of checkpoints, regulatory proteins, and the importance of DNA replication. 

• Role of checkpoints: 

• Critical control points in the cell cycle which act as quality control mechanisms and prevent the propagation of errors such as DNA damage or incomplete replication 

• Role of regulatory proteins: 

• Controls the progression of the cell cycle by triggering specific events such as DNA replication or mitosis 

• DNA replication is essential because each daughter cell receives a complete and identical genome copy, ensuring genetic continuity from generation to generation. 

Also, list and elaborate on the three essential steps every cell must go through in order to reproduce. 

1. DNA replication: The cell must accurately duplicate its genetic material, which ensures that each daughter cell receives a complete and identical copy of the genome 

2. DNA separation: The replicated DNA must be separated and distributed to the daughter cells so each daughter cell gets its copy of the genetic material. 

3. Cell division: The cell’s cytoplasm and other cellular components must be divided, resulting in two distinct daughter cells and completing the cell reproduction process. 

5. What model organism did Mendel utilize? Give three reasons why and explain. 

• The model organism Mendel utilized was the garden pea plant (Pisum sativum) because it is easy to grow and has a short generation time, allowing Mendel to conduct numerous experiments and observe multiple generations. Pea plants also exhibit several easily observable and distinct heritable traits, allowing Mendel to track the inheritance of specific traits from parent to offspring. Lastly, pea plants can both self-pollinate and cross-pollinate, and Mendel could control pollination easily, which was essential for conducting controlled experiments and accurately determining inheritance patterns. 

Also, describe Mendel’s experimental plan’s key elements and findings (laws). Please use a monohybrid cross in a Punnett square to provide an example. 

• Key elements: 

• Monohybrid and Dihybrid crosses 

• Findings (laws): 

• Law of Segregation: two alleles for a heritable character separate from each other and end up in different gametes 

• Law of independent assortment: each pair of alleles separates independently of other pairs of alleles during gamete formation 

• Law of dominance: The dominant allele determines the organism's appearance, whereas the recessive allele has no noticeable effect. 

• Monohybrid cross in a Punnet square: 

6. Explain the differences and similarities between epistasis and epigenetics. Please use examples to demonstrate your descriptions. 

• Differences: 

• Epistsasis involves gene-gene interactions, while epigenetics involves modifications to the DNA 

• Epistasis interactions are not heritable beyond the immediate offspring, whereas epigenetic changes can be heritable across multiple generations. 

• Similarities: 

• Both result in changes in how genes are expressed, leading to variations in phenotype. 

7. What is the relationship between genotype and phenotype, and how does heterosis play a role in this connection? 

• The relationship between genotype and phenotype is that genotype is an organism's genetic makeup, whereas phenotype is an organism's observable trait. 

• Heterosis plays a role in this connection because it causes f1 hybrids to exhibit traits surpassing those of their inbred parents, often leading to increased vigor, yield, and other desirable characteristics. 

Please explain heterosis using an example from plants or animals. Please use examples to demonstrate your descriptions. 

• An example of an animal is cross breeding different breeds of beef cattle such as cross breeding hereford and angus cattle. Herefords are known for excellent meat quality but they do have slower growth whereas angus cattle are known for a faster rapid growth and good fertility. 

What are some strategies to keep heterosis advantages beyond a terminal cross?  

• Some strategies to keep heterosis advantages beyond a terminal cross are rotational or composite breeding. 

8. How do different types of genetic inheritance patterns, such as incomplete dominance, complete dominance, overdominance, and codominance, influence trait expression? Please provide examples for each inheritance pattern. 

• Incomplete dominance influences trait expression by neither allele is completely dominant, its an intermediate blend between dominant and recessive traits. 

• Example: Red flowers and white flowers = pink flowers so heterozygous plants show a blended pink color rathern than red or white 

• Complete dominance is when one allele (the dominant) completely masks the expression of the other (recessive) 

• Example: In pea plants, purple flowers (P) are dominant over white flowers (p) so PP would result in purple and Pp would still result in purple because the dominant allele fully masks the recessive 

• Overdominance is when the heterozygous genotype exhibits a more beneficial trait compared to either homozygous genotype 

• Example: If an animal is resistant to a disease and is crossed with resistant but suffers with a deficieny then it will be resistant to both a disease and the deficiency. 

• Codominance is that both alleles are fully expressed simultaneously in heterozygous individuals 

• Example: human blood types such as AB where both A and B antigens are fully expressed rather than bledning 

Please speculate on how we could use these patterns to help agriculture. 

• We can use these patterns to help agriculture by developing high-yield crops, improve livestock health and productivity.