Cell Differentiation + Epigenetics + Phenotype

Through differential gene expression, where different genes in their DNA become active and get expressed.

A stimulus, such as a chemical signal, triggers the activation of certain genes.

mRNA is translated on ribosomes to produce proteins.

Transcription factors control the expression of genes by either stimulating or inhibiting transcription.

Activators stimulate gene expression by increasing the rate of transcription, while repressors inhibit gene expression by decreasing the rate of transcription.

An operon is a section of DNA that includes a cluster of structural genes that are transcribed together, and it functions by binding to transcription factors that either stimulate or inhibit transcription.

Transcription factors bind to specific DNA sites near the start of target genes.

The cell becomes irreversibly specialized, with permanent modifications to its structure and function.

Differential gene expression allows different cells to specialize and acquire unique structures and functions.

Transcription factors control the rate of transcription by either increasing or decreasing the rate of transcription.

It is a DNA sequence that RNA polymerase initially binds to, enabling a gene to be transcribed.

It binds to the operator site, preventing RNA polymerase from binding to the promoter region and blocking transcription.

It binds to the lac repressor, changing its shape and preventing it from binding to the operator site, allowing RNA polymerase to bind to the promoter region and initiate transcription.

Epigenetics is the study of heritable changes in gene function that do not involve a change in the base sequence of DNA. It involves the switching-on and switching-off of genes without altering the genetic code.

It adds a methyl group to cytosine bases, preventing RNA polymerase from binding to the promoter region and suppressing gene expression.

It adds an acetyl group to histone proteins, making the DNA less tightly wrapped around the histones and allowing RNA polymerase to bind to the promoter region and initiate transcription.

It removes acetyl groups from histone proteins, making the chromatin more condensed and preventing RNA polymerase from binding to the promoter region, resulting in gene repression.

Epigenetic changes can be passed on after cell division, affecting the expression of genes in daughter cells.

Epigenetic modifications, such as acetylation, can lead to the activation of inappropriate genes, increasing the risk of cancer.

Methylation typically represses gene expression, while acetylation typically activates gene expression.

Certain genes that are activated or deactivated in the original cell will also be activated or deactivated in the daughter cells.

To remove epigenetic marks, such as methylation and acetylation, allowing for a reset of gene expression in the zygote.

Continuous variation shows a range of values, while discontinuous variation shows distinct categories with no in-between variants.

Environmental factors can influence the expression of polygenic traits, such as height and skin color, by interacting with genetic factors.

Monogenic inheritance is influenced by one gene, showing discontinuous variation, while polygenic inheritance is influenced by multiple genes, showing continuous variation.

Epigenetic changes can occur in response to environmental factors, allowing daughter cells to be better adapted to the changed environment.

Acetylation of histones activates genes, allowing for gene expression.

Meiosis removes most acetylation and methylation, allowing for a reset of gene expression in the zygote.

Cancer can disrupt the cell cycle by bypassing critical checkpoints, allowing damaged DNA to be replicated and abnormal cells to divide.

Non-differentiated embryonic stem cells are totipotent and have not yet activated or deactivated genes, making them useful for research.