Molecular genetics Flashcards by Jasmine

is the branch of biology that studies the structure, function, and transmission of genetic material at the molecular level.

Molecular genetics

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It focuses on how genes are encoded, expressed, and regulated, influencing heredity and biological functions.

Molecular genetics

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is a technique that allows scientists to modify an organism’s DNA by adding,
deleting, sequences.

Gene editing

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This process can be used to correct genetic disorders, enhance traits, and study gene functions

Gene editing

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Purpose of Gene Editing (4)

Medical Applications
Agriculture
Scientific Research
Biotechnology:

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Types of Gene Editing (5)

CRISPR-Cas9
• TALENs (Transcription Activator-Like Effector Nucleases)
• Zinc Finger Nucleases (ZFNs)
• Base Editing
• Prime Editing

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These are engineered nucleases used for precise genome editing, created by fusing a DNA-binding domain derived from transcription activator-like (TALE) proteins to a DNA cleavage domain, like FokI, allowing for targeted DNA cutting

TALENs (Transcription Activator-Like Effector Nucleases)

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can be used to introduce precise insertion, deletion, or substitution of specific genes in order to alter the genome.

TALENs (Transcription Activator-Like Effector Nucleases)

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They are a versatile tool for genome editing in various organisms and cell types.

TALENs (Transcription Activator-Like Effector Nucleases)

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They have shown promise as a tool for genome editing in both in vitro and in vivo settings.

TALENs (Transcription Activator-Like Effector Nucleases)

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Advantages of TALENs (3)

Precise targeting;
Versatile:
Modular design

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Disadvantages of TALENs (2)

Mosaicism:
Off-target effects:

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ZFNs have a wide range of applications, including: 3

Gene therapy;
Research:
Developing new technologies

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engineered, artificial restriction enzymes that combine a zinc finger DNA-binding domain with a DNA-cleavage domain, allowing for precise targeting and editing of specific DNA sequences within a genome.

Zinc Finger Nucleases (ZFNs

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work by recognizing and binding to a specific DNA sequence, and then inducing a double-strand break at that location, which triggers the cell’s DNA repair mechanisms to modify or disrupt the gene at that site.

Zinc Finger Nucleases (ZFNs

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ZFNs are chimeric proteins, meaning they are made up of two distinct parts:

DNA-binding domain
DNA-cleavage domain

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This is composed of
multiple zinc finger motifs, each of which
recognizes a specific 3-base pair sequence on the
DNA

DNA-binding domain:

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: This is derived from the
FokI endonuclease, which cleaves DNA at a
double-stranded site

DNA-cleavage domain

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Advantage of Zinc Finger Nucleases (ZFNs): 3

High specificity:
Versatility
Potential for gene therapy

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a gene-editing technology that uses components
from CRISPR systems, along with other enzymes, to
directly modify DNA or RNA without causing double
stranded DNA breaks, enabling precise changes in
single DNA bases.

Base Editing

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can be
used to correct single-base mutations that cause
genetic diseases.

Base editing

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offer a promising
approach for treating genetic diseases by directly
modifying the DNA in affected cells.

Base editors

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is a “search-and-replace” genome
editing technology that allows for precise
modifications of cellular DNA without relying on donor DNA templates or double-strand breaks
(DSBs)

Prime editing

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Prime editing utilizes a fusion protein consisting of a catalytically impaired ____
fused to an engineered ____
enzyme

Cas9 endonuclease (nickase); reverse transcriptase

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has been used in animal models of genetic diseases, plants, and has shown promise for treating conditions like sickle cell disease and Tay Sachs disease

Prime editing

guides the Cas9 nickase to the target DNA site and provides the new genetic information to replace the target DNA nucleotides

Prime Editing Guide RNA (pegRNA)

is a gene-editing technology derived from a naturally occurring bacterial defense system, allowing scientists to precisely edit DNA sequences.

CRISPR

: Acts as molecular "scissors" to cut DNA at a targeted location.

Cas9 Enzyme

: Directs Cas9 to the specific DNA sequence

Guide RNA (gRNA)

class of CRISPR (2)

Class 1 (Multi protein complexes); Class 2 (Single protein effectors)

types of Class 1 crispr (3)

Type I, Type III, Type IV

types of Class 2 crispr (3)

Type II, Type V, Type VI

Uses multiple proteins for DNA targeting

Class 1 (Multi protein complexes)

Uses a single protein (Cas enzyme)

Class 2 (Single protein effectors)

examples of Class 2 (Single protein effectors) crisprs

CRISPR-Cas9, CRISPR Cas12, CRISPR-Cas13

refers to heritable changes in gene expression that do not alter the DNA sequence. Instead, they involve modifications to DNA and associated proteins, affecting how genes are turned "on" or "off."

Epigenetics

These modifications are influenced by environmental factors, diet, stress, and lifestyle and can sometimes be inherited across generations

Epigenetics

Mechanisms of Epigenetic Regulation (3)

DNA Methylation; Histones Modification; Non-Coding RNA (ncRNA) Regulation

The addition of a methyl (-CH₃) group to cytosine bases in the DNA sequence, usually at CpG islands

DNA Methylation

Enzymes Involved in dna methylation (2)

DNA methyltransferases (DNMTs) TET enzymes

these enzymes add methyl groups to DNA.

DNA methyltransferases (DNMTs)

these enzymes can remove methylation, allowing gene reactivation.

TET enzymes

Effects of DNA Methylation (3)

Gene silencing X-Chromosome Inactivation Genomic Imprinting

– Prevents transcription factors from binding to DNA, turning genes off

Gene silencing

– In female mammals, one X chromosome is silenced through methylation.

X-Chromosome Inactivation

– Only one parent's gene copy is expressed while the other is silenced

Genomic Imprinting

in____, improper DNA methylation leads to loss of gene expression in neurons, causing intellectual disabilities

Angelman syndrome

In ___, hypermethylation of tumor suppressor genes (e.g., p53, BRCA1) silences their function, allowing uncontrolled cell growth.

cancer

affect whether DNA is tightly packed (heterochromatin, inactive) or loosely packed (euchromatin, active) for gene expression.

Histone modifications

If: DNA is tightly packed= DNA is loosely packed=

tightly packed=heterochromatin, inactive loosely packed= euchromatin, active

Types of Histone Modifications (3)

Acetylation Methylation Phosphorylation

enzymes involved in acetylation (2)

Histone acetyltransferases (HATs) Histone deacetylases (HDACs)

enzymes that add acetyl groups to histones → DNA loosens, making genes active.

Histone acetyltransferases (HATs)

enzymes that remove acetyl groups → DNA tightens, making genes inactive

Histone deacetylases (HDACs) remove acetyl groups → DNA tightens, making genes inactive

enzymes involved in methylation (2)

Histone methyltransferases (HMTs); Histone demethylases (HDMs)

enzymes which add methyl groups → Can either activate or repress genes.

Histone methyltransferases (HMTs)

enzymes which remove methyl groups, changing gene expression.

Histone demethylases (HDMs)

Plays a role in DNA repair and stress responses.

Phosphorylation

increases the expression of tumor suppressor genes in cancer therapy

Histone acetylation

is linked to neurodegenerative diseases like Alzheimer’s disease.

Histone deacetylation

are RNA molecules that do not code for proteins but regulate gene expression

Non-coding RNAs

Types of ncRNAs: 3

MicroRNAs (miRNAs)– Long non-coding RNAs (lncRNAs) Piwi-interacting RNAs (piRNAs)

Bind to mRNA and prevent translation into proteins (gene silencing).

MicroRNAs (miRNAs)–

– Regulate chromatin remodeling and gene transcription.

Long non-coding RNAs (lncRNAs)

Involved in protecting the genome from transposable elements (jumping genes).

Piwi-interacting RNAs (piRNAs)–

__ and ___ turn off unnecessary genes while activating cell-type-specific genes.

DNA methylation and histone modifications

In muscle cell differentiation, myogenic genes (related to muscle formation) are activated via ___

histone acetylation

Certain genes are only expressed from one parent’s allele due to epigenetic silencing.

Genetic Imprinting

in genetic imprinting, this gene is only expressed from the paternal allele.

IGF2 gene (Insulin-like Growth Factor 2)

Disorders due to imprinting errors: 2

Prader-Willi Syndrome (PWS) Angelman Syndrome–

Paternal genes are lost, causing obesity and intellectual disabilities.

Prader-Willi Syndrome (PWS)–

–Maternal genes are lost, leading to neurological problems.

Angelman Syndrome

Folic acid, vitamin B12, and polyphenols influence ___

DNA methylation

___ can alter DNA methylation and increase mental health risks.

Early-life trauma

Chemicals like ___disrupt methylation and can lead to diseases

BPA

Children of malnourished mothers had altered DNA methylation, increasing risk for diabetes and heart disease later in life.

Dutch Hunger Winter (1944–45):

____of tumor suppressor genes silences cancer-fighting genes.

Hypermethylation

____of oncogenes leads to uncontrolled cell division

Hypomethylation

____gene hypermethylation is associated with breast and ovarian cancer.

BRCA1

Altered histone modifications contribute to neurodegeneration

Alzheimer’s Disease:

Schizophrenia & Depression: methylation patterns affect neurotransmitter regulation.

Abnormal DNA

Epigenetic changes in insulin related genes contribute to glucose metabolism issues

Diabetes:

Epigenetic Therapy/strategies (3)

DNA Methylation Inhibitors; Histone Deacetylase (HDAC) Inhibitors; CRISPR-based Epigenetic Editing

mechanism of ___:Reactivate silenced tumor suppressor genes

DNA methylation inhibitors

mechanism of___: Open chromatin structure to allow gene activation

Histone Deacetylase (HDAC) Inhibitors

mechanism of __: Directly modifies epigenetic marks at specific genes

CRISPR-based Epigenetic Editing

example of DNA Methylation Inhibitors

5-azacytidine (for leukemia)

example of Histone Deacetylase (HDAC) Inhibitors

Vorinostat (for lymphoma)

Regions with many CG sequences

CpG island

Molecular genetics Flashcards

(89 cards)