Unit 1: Structure of DNA and Replication
In Unit 1, the structure of DNA is described as a double strand of nucleotides forming a double helix. It consists of deoxyribose sugar, phosphate, and base, with a sugar phosphate backbone. Complementary bases pair as A-T and C-G, with hydrogen bonds between bases. DNA also has an antiparallel structure with deoxyribose and phosphate at 3' and 5' ends, along with proteins/histones. DNA unwinds into 2 strands, needing a primer to start replication. DNA polymerase adds nucleotides to the 3' end of the strand, and in one direction. One strand is replicated continuously, while the other is in fragments, which are joined by ligase.
Unit 1: Gene Expression in Eukaryotes
Under the gene expression in eukaryotes section, production of mRNA and translation of mRNA are discussed. RNA polymerase unzips/unwinds DNA or separates DNA into two strands, with hydrogen bonds between strands breaking, aligning/joining/attaching RNA nucleotides with their complementary nucleotides/bases on DNA (template) to produce a primary transcript. Exons are coding, and introns are non-coding regions, where introns are removed or exons are retained. They are spliced/joined together to form mature mRNA. tRNA has an anticodon and an amino acid attachment site, binding to/carrying/collecting specific/correct amino acids, carrying them to ribosomes. Translation involves the formation of peptide bonds between amino acids or the formation of a polypeptide.
Unit 1: Stem Cells
Stem cells are unspecialised/undifferentiated cells that have the capacity to divide and differentiate into specialised cells for various functions. There are adult and embryonic stem cells, with the former differentiating into cells needing to be replaced while the latter differentiate into all cell types. Stem cell research provides valuable information on cell processes and can be used therapeutically to repair damaged or diseased organs, tissues, or cells. However, ethical issues related to stem cell research, such as the use of induced pluripotent stem cells or nuclear transfer techniques, must be taken into consideration.
It is clear from the answers provided for SQA Higher Biology Extended Response that a thorough understanding of DNA structure, gene expression in eukaryotes, and stem cell research and therapy is crucial for success in this subject matter.
For more detailed understanding, it is recommended to refer to higher biology past papers by topic with answers, SQA higher biology past papers, and SQA higher human biology past papers. Furthermore, the study of DNA structure and replication can be supplemented with DNA structure and replication PDF, DNA structure and replication worksheet, DNA structure and replication answer key, and DNA structure and replication diagram. Similarly, a better grasp of gene expression in eukaryotes can be achieved by utilizing resources such as DNA structure and function PDF, DNA structure and replication PPT, and gene expression in eukaryotes PDF, notes, slideshare, and example resources.
