AP Bio Unit 6

Question 1

What is gel electrophoresis?

Answer 1

Gel electrophoresis is a laboratory technique used to separate and analyze macromolecules such as DNA, RNA, and proteins based on their size and charge. The technique relies on the principle of electrophoresis, which involves the movement of charged molecules in an electric field.

Question 1

What are the steps of DNA replication

Answer 1

1. Helicase unzips the DNA strands
2. RNA primase adds an RNA primer to tell DNA polyermerase where to start on the leading strand (3’ to 5’)
3. On the lagging strand Okazaki fragment are made using RNA Primase and DNA Polymerase
4. DNA Ligase connects the okazaki fragments
   Topoisomerase relaxes coiled DNA to avoid structural damage
   Single stranded binding proteins ensure the two strands stay seperate

Question 2

What describes DNA replication?

Answer 2

Semiconservitive

Question 3

What is the central dogma?

Answer 3

DNA creates mRNA via transcription and mRNA is translated into amino acids that form proteins that do everything in your body

Question 4

How does transcription work?

Answer 4

RNA polymerase binds the complementary base pairs of a DNA strand to form pre-mRNA

A 5’ cap (modified guanine) and a poly A tail to the 3’ end to protect the mRNA and form pre-mRNA

The pre-mRNA has introns and exons, and a protein called splicesome removed the introns.

Question 5

What is alternative gene splicing?

Answer 5

The different ways that pre-mRNA can be spliced

Question 6

What are the parts and sites of a ribosome?

Answer 6

There are two subunits: The large and small subunit. mRNA translates on the small ssubunit

There is the A, P, and E sites. The A stands for the amino site. P is the peptide site. E is the exit site.

Question 7

What are the difference kinds of RNA and their functions?

Answer 7

mRNA: messenger RNA transcribed from DNA and sent to the ribosomes for translation
rRNA: makes up ribosomes
tRNA: transfer RNA. Carries an amino acid to the ribosome to make a polypeptide chain

Question 8

How does translation work?

Answer 8

tRNAs contain anti-codons that bind to 3 consecutive nitrogenous bases and an amino acid it carries. The tRNA finds its curresponding match at the A site.

The ribosome moves the first tRNA to the P-site, where the amino acid carried by the tRNA is added to the polypeptide chain.

At the E-site the tRNA leaves the mRNA strand

Question 9

What is the difference in gene expression between prokaryotes and eukaryotes?

Answer 9

Transcription and translation occours at the same time in the cytoplasm in prokaryotes

Question 10

How is gene expression regulated?

Answer 10

It is usually regulated before transcription (pre-transcriptional regulation) with which genes are able to be unwound and read by RNA polymerase.

Transcription factors can encourage or inhibit this from happeneing

Question 11

What is a promotor sequence?

Answer 11

It is what RNA Polymerase binds to to form mRNA.

Question 12

What are epigenetic changes?

Answer 12

Changes to the packaging of DNA that alter the abillity of transcription machinery to access a gene.

Question 13

What are Histones, methylation, and acetlyation?

Answer 13

Histones are proteins that help condese DNA into chromatin.

Methylation causes histones to tighten up DNA, making it harder to read, and acetylation causes histones to loosen DNA making it easier to read.

Question 14

What is an operon?

Answer 14

It is a system that regulates the expression of genes in prokaryotes. It consistes of a promoter, operator, and a set of related genes. The operator region is where a repressor can bind to to stop transcription.

Examples are the lac operon for lactose and trp operon for tryptophan

Question 15

What is the eukaryotic version of an operon?

Answer 15

Enhancers are found on eukaryotic DNA and bind to transcription factors, which increase the expression of certain genes by making the DNA more accessible or increasing the rate of transcription.

Question 16

How does epigenetics affect enhancers?

Answer 16

The activity of enhancers can be influenced by epigenetic mechanisms such as DNA methylation, histone modifications, and chromatin remodeling. For example, methylation of DNA near enhancer regions can inhibit the binding of transcription factors and suppress enhancer activity, leading to decreased gene expression. Conversely, histone modifications such as acetylation or methylation can enhance enhancer activity by altering chromatin structure and promoting the recruitment of transcriptional machinery.

Question 17

Whar is post-transcriptional regulation?

Answer 17

Sometimes, a cell creates mRNA but wants to kill it. RNAi (RNA interference) molecules bind complementary base pairs to that RNA to create double stranded RNA. when double stranded RNA is formed, that creates a a signal it should be destroyed.

siRNA (Short interfereing) is double stranded RNA used to regulate RNA. it is cut from large dsRNA or double stranded RNA

Question 18

What is morphogenesis?

Answer 18

The process by which a dividing embryo regulates the genes of its cells to allow them to specialize. Cells cannot despecialize. Apoptosis is important for this. Homeotic genes change future cells into what they will specialize in.

Question 19

What are the base-substitution mutations?

Answer 19

Nonsense: cause the codon to change to a stop codon
Missense: Causes the codon to produce an different amino acid
Silent: Does nothing