Inhertance and Genetics Flashcards
What are nucleosomes made from?
Nucleosomes are made from DNA wrapped around histone proteins
Nucleosomes are the fundamental units of chromatin structure.
What is the function of nucleosomes?
Nucleosomes help to supercoil the DNA and regulate transcription in eukaryotes
This regulation is crucial for gene expression control.
What is the structure of a nucleosome?
A nucleosome consists of 8 histone proteins: 2 each of H2A, H2B, H3, and H4
The nucleosome is often visualized as ‘beads on a string’ of DNA.
What role does H1 play in nucleosomes?
H1 is a linker histone that helps to stabilize the structure of the nucleosome
It binds to the DNA where it enters and exits the nucleosome.
What type of cell would you NOT find nucleosomes?
You would NOT find nucleosomes in prokaryotic cells
Prokaryotes have a simpler structure lacking histone proteins.
How can the modification of the N-terminal tail from the nucleosome regulate gene expression?
Acetylation of the N-terminal tail allows expression, while methylation suppresses it
These modifications alter the interaction of nucleosomes with transcription factors.
What is the composition of eukaryote chromosomes?
Eukaryote chromosomes are linear DNA molecules associated with histone proteins
This structure is essential for DNA packaging and regulation.
What is ‘linker’ DNA?
‘Linker’ DNA refers to the stretch of DNA between nucleosomes
It connects adjacent nucleosomes and is crucial for chromatin organization.
What regulates gene expression?
Gene expression is regulated by proteins that bind to specific base sequences in DNA.
What impacts gene expression?
The environment of a cell and of an organism has an impact on gene expression.
What is imprinting in gene expression?
The epigenome does not get erased completely and results in imprinting.
What is an example of imprinting?
Lions are an example of how the father being a lion still gives the offspring traits linking it to its mother due to imprinting.
Imprinting involves epigenetic tags.
How does methylation affect tumor suppressor genes?
Methylation of tumor suppressor genes can impact their expression.
How does the lac operon in E. coli control gene expression?
In E. coli, the lac operon uses a repressor protein that binds to the promoter region for lactase. The presence of lactose will deactivate the repressor protein and allow production of lactase.
What changes in the E. coli environment cause changes in lactase production?
When lactose is present and glucose is low, glucose destroys the repressor, allowing more lactase production.
What is transcription?
Transcription is the synthesis of mRNA copied from the DNA base sequences by RNA polymerase.
In which direction does transcription occur?
Transcription occurs in a 5’ to 3’ direction.
How can transcription be regulated?
Transcription can be regulated by proteins that bind to the DNA.
What is the promoter region in transcription?
The promoter region is a sequence of DNA where RNA polymerase binds to initiate transcription.
What is the TATA box?
The TATA box is a specific DNA sequence within the promoter region that helps position RNA polymerase.
What role do transcription factors play?
Transcription factors are proteins that assist in the binding of RNA polymerase to the promoter region.
What is DNA methylation?
DNA methylation is the addition of methyl groups to DNA, which can activate or repress transcription.
How can the environment influence epigenetic factors?
The environment can trigger heritable changes in epigenetic factors, affecting gene expression.
What do monozygotic twin studies show about methylation patterns?
Monozygotic twin studies show that methylation patterns can change with age, indicating environmental influence.
Will identical twins become more or less similar in characteristics as they age?
Identical twins will become less similar due to mutations and epigenetic factors.
List three processes that change gene expression in chromatin.
Methylation, acetylation, and phosphorylation of amino acid tails of histones.
How do epigenetic tags influence inheritance?
Epigenetic tags can be inherited, and changes in chromatin structure can affect gene accessibility.
Give an example of an environmental factor affecting heritable DNA.
Lions show how environmental factors can influence traits passed to offspring through imprinting.
What is imprinting in the context of epigenetics?
Imprinting refers to the inheritance of epigenetic tags that affect gene expression without erasing the epigenome.
What is crossing over?
Crossing over is the exchange of DNA material between non-sister homologous chromatids.
What does crossing over produce?
Crossing over produces new combinations of alleles on the chromosomes of the haploid cells.
What is the result of unlinked genes during meiosis?
Unlinked genes segregate independently as a result of meiosis.
What does it mean for gene loci to be linked?
Gene loci are said to be linked if they are on the same chromosome.
How does crossing over promote genetic variation?
Crossing over and random orientation promotes genetic variation.
How does fusion of gametes contribute to genetic variation?
Fusion of gametes from different parents promotes genetic variation.
What are the three processes in sexual reproduction that increase variation?
- Crossing over: when non-sister chromatids exchange DNA segments.
- Independent assortment: when chromosomes segregate during meiosis.
- Random fertilization: fusion of gametes from different parents.
What makes independent assortment possible?
Independent assortment of genes is due to the random orientation of pairs of homologous chromosomes in meiosis 1.
How does the orientation of homologous chromosomes affect variation?
Orientation of pairs of homologous chromosomes prior to separation is random, affecting variation in a population.
What happens to alleles during meiosis?
The two alleles of each gene separate into different haploid daughter nuclei during meiosis.
What is the result of gamete fusion?
Fusion of gametes results in diploid zygotes with two alleles of each gene that may be the same allele or different alleles.
