Unit 5 Reflection

Unit 5 was about genetic code, DNA replication, making proteins, mutations, and gene expression and regulation. DNA is a double helix made up of two strands twisted around each other like a twisted ladder. DNA is made up of nucleotides. Nucleotides are made up of 3 parts: a nitrogen base (A, T, C, G), a phosphate group, and a sugar (deoxyribose). Phosphate and sugar make up the sides of the ladder and the bases are the steps. DNA is anti-parallel. This means that each nucleotide covalently bonds with another. Nitrogen bases come in two types: double rings called purines(adenine and guanine), and single rings called pyrimidines (thymine and cytosine). Adenine always pairs with thymine, and Cytosine always pairs with guanine. Code is a system of words or symbols that are substituted for other words.

Semi-conservable replication is the process of creating two identical strands of DNA from one original strand. Two strands end up with half of the original strand. First, enzyme unzips DNA by breaking down hydrogen bonds that hold nitrogen bases together. Then, DNA polymerase add matching nucleotides to each strand. The result is two identical strands of DNA molecules that form are identical to the original DNA molecule.

The central dogma of biology is that information flows from DNA to RNA to proteins. Proteins make up out traits (phenotypes). RNA is single-stranded, has a ribose,contains uracil, and is a temporary copy of DNA. RNA delivers a copy to the ribosomes, and the ribosome uses this RNA copy to make proteins. Transcription is a process in the nucleus where RNA polymerase reads and copies the DNA code (gene) for a protein as mRNA. In the process of transcription, DNA unzips, RNA polymerase matches spare nucleotides to make an RNA strand,and mRNA is produced and leaves the nucleus for the cytoplasm. Translation is a process that takes place in the cytoplasm. First mRNA arrives at the ribosome. Then, the ribosome reads mRNA three bases at a time and transcribes the DNA language into amino acids. Each three-base sequence is known as a codon. Each codon codes for one amino acid.

A mutation is a change in DNA code (genes.) The effect can be none and sometimes it can be fatal. Mutagen is anything that causes a mutation. Mutations can happen naturally too. Point mutations are a change in one or two base pairs. These types of mutations are very small and common. A substitution is a change in which one nucleotide is substituted for another. The two types of frameshift mutations are insertion and deletion. Insertion is a mutation where one extra base pair is put in code. Deletion is a mutation in which one base pair is left out of the code. Inversion is a mutation where DNA breaks off and bonds in reverse order. Translocation is the part of a chromosome that breaks off and bonds with another. Mutations cause changes in DNA which cause changes in life. Proteins are essential to life.

This is a picture of an RNA strand being translated to an amino acid.

Gene expression is the process of a gene being used to produce a gene product or phenotype. Gene regulation is a mechanism used by cells to increase or decrease the expression of a gene. Every cell in your body has the same DNA but not all cells look the same. Cells look different because each type of cell expresses or turns on genes specific to those cells. Environment can affect how and when genes are expressed. Gene regulation is the process where cells do not want to waste energy or overexpress genes so they have many steps that are used to control gene expression. A promoter is the location on DNA where RNA polymerase attaches. An operon is a series of genes used to control the expression of a single gene. The operator is a “switch” or segment of DNA at the start of a gene that prevents or allows RNA polymerase from attaching and reading the gene. Eukaryotic regulation is much more complicated than bacterial regulation. EXons are EXpressed and introns are sequences that are cut out. Histones are proteins that allow DNA to coil. Nucleosomes are DNA that is wrapped twice around like a histone. Genes whose promoters are wrapped up in nucleosomes are not expressed. Different enzymes are involved in breaking histones free or binding them up to control gene expression. This is passed to future cells during development.
I really liked learning about making proteins and DNA. I had a difficult time on the protein synthesis lab because I did not understand how to convert a DNA strand to an RNA strand. After going back and watching the vodcast, I understood how to convert DNA to RNA. I also struggled in understanding the last vodcast. The vodcast was about gene expression and requlation. I didn't know the different parts of the operon. After doing the do now in class, I had a better visual understanding of an operon.

This is a picture from the protein synthesis lab that was difficult.