1What is the main aim of studying gene expression and regulation?
To understand how genes are controlled and how this relates to development and disease
2What does DNA represent in living cells?
The blueprint of the cell
3Why is regulation of gene expression important?
It determines cell function, development, and responses to the environment
4How is DNA organised in eukaryotic cells?
Packaged with proteins into chromosomes
5What is chromatin?
DNA complexed with histone proteins
6What is the basic repeating unit of chromatin?
The nucleosome
7How much DNA is wrapped around a nucleosome core?
146 base pairs
8What proteins make up the nucleosome core?
2 copies each of histones H2A, H2B, H3, and H4
9What connects adjacent nucleosomes?
Linker DNA
10How long is linker DNA?
Approximately 20–80 base pairs
11What histone is associated with linker DNA?
Histone H1
12What structure does nucleosome organisation produce?
Beads-on-a-string chromatin (10 nm fibre)
13Does chromatin usually exist as beads-on-a-string in living cells?
No, it is usually more compact
14What is the 10 nm fibre?
Extended nucleosome filament (beads-on-a-string)
15What is the 30 nm fibre?
Coiled chromatin fibre formed from the 10 nm fibre
16What role does histone H1 play in chromatin structure?
Required for formation of the 30 nm fibre
17How is the 30 nm chromatin fibre further organised?
Into looped domains
18What size are chromatin looped domains?
Tens to hundreds of kilobases
19What anchors looped domains within the nucleus?
The nuclear matrix
20What characterises metaphase chromosomes?
Highly condensed chromosomes with low gene activity
21What characterises interphase chromosomes?
Less condensed chromatin with higher gene activity
22How many chromosomes are in the human karyotype?
46 chromosomes arranged in 23 pairs
23What components make up chromosomes?
DNA, RNA, and proteins (mainly histones)
24What are telomeres?
Protective ends of chromosomes
25What are centromeres?
Regions where sister chromatids attach and spindle fibres bind
26What is DNA condensation?
Compacting DNA so it fits into the nucleus
27How compact is human DNA in cells?
Condensed approximately 10,000–20,000 times
28Does DNA quantity reflect organism complexity?
No
29What is gene expression?
The process by which genetic information is used to produce gene products (RNA/protein)
30What is the flow of genetic information?
DNA → RNA → protein
31What is transcription?
Synthesis of RNA from a DNA template
32What is translation?
Synthesis of a polypeptide/protein from an RNA template
33Where do transcription and translation occur in prokaryotes?
Both occur in the cytoplasm
34Where does transcription occur in eukaryotes?
In the nucleus
35Where does translation occur in eukaryotes?
In the cytoplasm (on ribosomes)
36What are the basic components of a eukaryotic gene?
Exons and introns
37What are exons?
Coding regions retained in mature mRNA
38What are introns?
Non-coding regions removed during RNA processing
39What is RNA splicing?
Removal of introns and joining of exons
40What is alternative splicing?
Different patterns of intron removal/exon joining to form different mRNAs from the same gene
41What is the result of alternative splicing?
Multiple protein products from one gene
42Why is alternative splicing important?
Increases protein diversity
43What is gene regulation?
Control of when, where, and how much a gene is expressed
44Why does the genome regulate gene expression?
To respond to developmental and environmental signals
45What are major sites of gene control?
Chromatin structure, transcription, RNA processing/transport, translation, and RNA/protein stability
46What is epigenetic control?
Heritable changes in gene expression without changes to DNA sequence
47How do epigenetic changes affect gene expression?
They change chromatin accessibility and gene activity
48What role do genes play in development?
They control cell fate and body patterning
49What are Hox genes?
Genes that control body plan and developmental patterning
50What is gene sequencing?
Determining the order of nucleotides in DNA
51Why is gene sequencing important?
Helps investigate gene structure, variation, and function
52Approximately how many genes are in the human genome?
About 20,000
53What is transcriptomics?
The study of all RNA transcripts (gene expression) in a cell/tissue
54What are inherited mutations?
Genetic changes passed from parents to offspring
55What are acquired mutations?
Genetic changes that occur during life (not inherited)
56What are complex genetic diseases?
Diseases involving multiple genes (often with environmental effects)
57What factors contribute to multifactorial diseases?
Genetic, environmental, and lifestyle factors
58What is a key conclusion about the genome?
It is flexible and highly regulated