5.0 (3 reviews)
Created by
This set contains the content understandings, applications, skills and nature of science syllabus statements for IB Biology topic 7.2: Transcription and Gene Expression.
Students also viewed
Acids and Bases
48 terms
Lab exam 2
53 terms
Mutations of Genes
33 terms
Maths AA SL - vocabulary
105 terms
Genetics exam #2
96 terms
Terms in this set (29)
Gene regulation is the process of controlling which genes in a cell's DNA are expressed (used to make a functional product such as a protein). Different cells in a multicellular organism may express very different sets of genes, even though they contain the same DNA.
Gene expression is regulated to ensure that the correct proteins are made when and where they are needed. Regulation may occur at any point in the expression of a gene, from the start of the transcription phase of protein synthesis to the processing of a protein after synthesis occurs.
Gene expression is regulated to ensure that the correct proteins are made when and where they are needed. Regulation may occur at any point in the expression of a gene, from the start of the transcription phase of protein synthesis to the processing of a protein after synthesis occurs.
Gene expression can be controlled by turning on/off genes at different times so only specific mRNA is produced through transcription. In eukaryotic cells, most genes are turned off (not being transcribed) at any one time. Gene expression is primary controlled by proteins called transcription factors, which bind to DNA to either increase or decrease transcription by enhancing or inhibiting the ability of RNA polymerase to bind to the promoter.
When DNA is coiled around histone proteins in a methylated nucleosome, the transcription factors can not bind to DNA. This will "silence" a gene so it will not be transcribed.
When acetylated, nucleosome will uncoil. This will expose the DNA, allowing transcription factors to bind. As a result, a genes will be accessible for transcription.
Hormones and environmental chemicals can interact with transcription factors to indirectly affect gene expression. For example, the plant hormone auxin interacts with transcription factors to regulate gene expression in plant meristems.
When DNA is coiled around histone proteins in a methylated nucleosome, the transcription factors can not bind to DNA. This will "silence" a gene so it will not be transcribed.
When acetylated, nucleosome will uncoil. This will expose the DNA, allowing transcription factors to bind. As a result, a genes will be accessible for transcription.
Hormones and environmental chemicals can interact with transcription factors to indirectly affect gene expression. For example, the plant hormone auxin interacts with transcription factors to regulate gene expression in plant meristems.
The protein responsible for brown/black coloration in the skin and hair/fur of many animals, including humans, is called melanin, which is produced in a biological pathway regulated by the enzyme tyrosinase. Himalayan rabbits (and Siamese cats) carry "temperature sensitive tyrosinase genes" which controls fur pigmentation. The genes are expressed differently depending on temperature - the cooler the body, the darker the fur!
The development of a flower by an angiospermatophyta is due to differentiation by cells in the shoot apex. The change in gene expression is in response to the change of light/dark cycle in the environment. Different genes are expressed in different regions of the tip of the shoot before, during and after formation of a flower.
The development of a flower by an angiospermatophyta is due to differentiation by cells in the shoot apex. The change in gene expression is in response to the change of light/dark cycle in the environment. Different genes are expressed in different regions of the tip of the shoot before, during and after formation of a flower.
Methylation of DNA represents one of the most important epigenetic mechanisms involved in the control of gene expression in eukaryotic cells. Methylation can change the activity of a DNA segment without changing the sequence. When a methyl group (-CH3) is added to the DNA, the DNA will remain tightly coiled in a nucleosome, thereby inhibiting transcription factors from initiating transcription (which keeps the genes turned "off")
When an acetyl group (−COCH₃) gets added to a histone protein of a nucleosome, it has the effect of changing the overall charge of the histone tail from positive to neutral. The change in charge disrupts the attraction of DNA to the histone, leading to weaker binding of the DNA to the histone proteins. The DNA becomes more accessible to transcription factors, which leads to an increase the expression of genes (turning the genes "on")..
Transcription is the process by which the information in a strand of DNA is copied into a complementary molecule of messenger RNA (mRNA). The newly formed mRNA copies of the gene then serve as blueprints for protein synthesis during the process of translation. Transcription is carried out by an enzyme called RNA polymerase and a number of accessory proteins called transcription factors.
Initiation is the beginning of transcription. It occurs when the enzyme RNA polymerase binds to a region of the DNA upstream of the gene at a specialized sequence called the promoter. This signals the DNA to unwind so the enzyme can ''read'' the bases in one of the DNA strands. The enzyme is now ready to make a strand of mRNA with a complementary sequence of bases.
Transcription factors are proteins that bind to enhancer or promoter regions of the DNA and interact to activate the transcription of a particular gene.
Transcription factors are proteins that bind to enhancer or promoter regions of the DNA and interact to activate the transcription of a particular gene.
Transcription elongation is the process in which an RNA chain complementary to the template strand of DNA is synthesized as RNA polymerase moves along DNA. RNA polymerase unwinds and separates the two strands of DNA, exposing 10-20 DNA bases for pairing with RNA nucleotides. RNA polymerase reads the unwound DNA strand and builds the mRNA molecule, using complementary base pairs (adenine with uracil and cytosine with guanine). Hydrogen bonds form between the RNA nucleotide and complementary base on the DNA strand.
Transcription is the synthesis of RNA complementary to one strand (the coding "antisense" strand) of DNA.
During initiation, RNA polymerase enzyme attaches to sequence of DNA known as promoter.
During elongation, the RNA polymerase unwinds and separates the two strands of DNA, exposing 10-20 DNA bases for pairing with RNA nucleotides. Complementary RNA nucleoside triphosphates are temporarily hydrogen bonded to the DNA bases on the antisense strand (adenine with uracil and cytosine with guanine). Hydrolysis of two of the phosphates on RNA nucleoside triphosphates occurs, providing the energy required to build the RNA polymer in the 5′ → 3′ direction.
During termination, the RNA polymerase reaches a terminator sequence of DNA which signals the end of the gene and causes the RNA polymerase and newly synthesized RNA molecule to separate completely from DNA. The DNA rewinds.
During initiation, RNA polymerase enzyme attaches to sequence of DNA known as promoter.
During elongation, the RNA polymerase unwinds and separates the two strands of DNA, exposing 10-20 DNA bases for pairing with RNA nucleotides. Complementary RNA nucleoside triphosphates are temporarily hydrogen bonded to the DNA bases on the antisense strand (adenine with uracil and cytosine with guanine). Hydrolysis of two of the phosphates on RNA nucleoside triphosphates occurs, providing the energy required to build the RNA polymer in the 5′ → 3′ direction.
During termination, the RNA polymerase reaches a terminator sequence of DNA which signals the end of the gene and causes the RNA polymerase and newly synthesized RNA molecule to separate completely from DNA. The DNA rewinds.