The presence of circular dna in mitochondria and chloroplasts suggests that these organelles evolved from ___.
1 answer:
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Explanation:
B) False
Multiple mutations in several protooncogenes and tumor suppressor genes are required to form cancer
Cancer-causing genes, or oncogenes, develop from protooncogenes which regulate normal cell division. They may undergo mutations that alter gene expression, disrupt cell regulation and lead to the transformation of normal cells into tumor cells- their resulting proteins are abnormal or not formed. Tumor suppressor genes, which can halt unregulated cell growth and division, may also become mutated.
Each individual inherits 2 copies of a gene from their parents- a single mutation in one of these does not directly lead to cancer. Multiple activated oncogenes, in turn produce damaged, non functional proteins and together contribute to forming cancers.
Further Explanation:
During the process of cell division, spontaneous changes within the genome can arise. These mutations are errors occur when copies of the DNA within the cell are made; mutations may range from small changes called single nucleotide polymorphisms, to large scale deletions, and additions which span multiple genes. There are two types:
- somatic: these only occur within certain cells, and arise from environmental factors such as UV light
- hereditary: occur within germ cells of the parent and later the fertilized egg which forms a zygote; these are present within all cells of the new organism.
Sequences of DNA make up genes which can have different forms called alleles. DNA, which makes up the genotype, is transcribed into mRNA and later translated into amino acids which are linked together by rRNA to form proteins which make up the phenotype of an organism. Mutations in DNA sequences affect the corresponding mRNA and thus the protein encoded.
Learn more about mutations at brainly.com/question/4602376
Learn more about DNA and RNA at brainly.com/question/2416343?source=aid8411316
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