Studied by 0 peopleHuman Genetics
Science of human variation
Medical Genetics
Science of abnormal human variation
Clinical Genetics
Branch of medicine involved with individuals and families with, or at risk of, conditions which may have a genetic basis
What are contained within the nucleus?
chromosomes
Chromosomes
genetic material
What are the structures of the nucleus?
Nuclear Envelope
Nuclear Pore
Nuclear Envelope
separates DNA from cytoplasm
What do nuclear pores allow for?
allow for communication
What cellular processes occur within the nucleus?
DNA replication and Transcription
What all are contained within the cytoplasm?
Cytosol
Endoplasmic Reticulum
Mitochondria
Golgi Apparatus
Lysosomes
Peroxisomes
Cytosol
semifluid with structural and soluble elements
Endoplasmic Reticulum
interconnecting channels
What can be found in the ER?
Ribosomes
Ribosomes
translation machinery made of RNA and proteins
What cellular process is carried out in the ER?
Translation
Mitochondria
energy producing organelle
Golgi Apparatus
secretes cellular products
Lysosomes
degrades waste material and breaks down polymers
Peroxisomes
degrades waste material and removes toxic oxidation products
What does a nucleotide contain?
Nitrogenous base
Sugar molecule (Deoxyribose)
Phosphate molecule
What are the two different types of nitrogenous bases?
Purines and Pyrimidines
Which are the purines?
A. Adenine
B. Cytosine
C. Guanine
D. Thymine
A. Adenine
C. Guanine
Which are the pyrimidines?
A. Adenine
B. Cytosine
C. Guanine
D. Thymine
B. Cytosine
D. Thymine
What type of bond joins nucleotides together?
a phosphodiester bond
On what C do phosphodiester bonds connect?
•Connect 3’ and 5’ C between sugars
What type of bonds hold together the DNA double helix?
hydrogen bonds
How do DNA strands run?
DNA strands run antiparallel to one another
Why is located on the 5’ end of the DNA strand?
a terminal phosphate
Why is located on the 3’ end of the DNA strand?
a terminal hydroxyl
What is the primary coil of a chromosome structure?
double helix that connects the two strands of DNA via H-bonds and coil
What is the secondary coil of a chromosome structure?
DNA wraps around histone proteins to create a nucleosome
How many histone proteins makes up a nucleosome?
8 histone proteins
What are the histone proteins that make of the nucleosome?
H2A
H2B
H3
H4
What is the tertiary coil of the chromosome structure?
nucleosomes wrap and form chromatin fibers
Solenoid Model
Tight winding of chromatin DNA to make up a spring-like helical coil
How many chromosomes do humans have?
23 chromosomes
How many protein coding genes are in human chromosomes?
20,000-25,000
Individuals inherit how many copies of each chromosome from each parent?
inherit one copy of each chromosome
What type of DNA is transcribed and translated into proteins?
A. Coding DNA
B. Non-Coding DNA
A. Coding DNA
What type of DNA is extragenic DNA?
A. Coding DNA
B. Non-Coding DNA
B. Non-Coding DNA
What are the different types of DNA?
Nuclear genes
Extragenic DNA
Mitochondrial DNA
How many genes are in the nuclear genome?
20,000 genes
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Heterochromatin
the area of the chromosome which is darkly stained with a DNA-specific stain and is in comparatively condensed form
Euchromatin
the area of the chromosome which is rich in genes that actively participate in the transcription process
What type of DNA is this?
Non-coding DNA
Highly Condensed
A. Euchromatin
B. Heterochromatin/Centromeric
B. Heterochromatin/Centromeric
What type of DNA is this?
Coding DNA
A. Euchromatin
B. Heterochromatin/Centromeric
A. Euchromatin
Where are genes located?
within chromosomes
What do Single-Copy Genes code for?
code for polypeptides with specific functions
Where are DNA sequences located on a chromosome?
found in exons
Multigene Families
Genes with similar functions that are made from gene duplication and evolutionary divergence
Where are multigene families found?
found in clusters of genes on chromosome
What are the two types of multigene families?
Classic gene families
Gene superfamilies
Which type of multigene family is described below?
Sequence homology
DNA sequences are similar
i.e. tRNA genes
A. Classic gene families
B. Gene superfamilies
A. Classic gene families
Which type of multigene family is described below?
Functional homology
Structure is similar
i.e. HLA genes and T-cell receptor genes have similar structure to immunoglobulin genes
A. Classic gene families
B. Gene superfamilies
B. Gene superfamilies
Inton
non-coding intervening sequences
Exon
coding sequences of gene
Satellite DNA
DNA repeats that are transcriptionally inactive
Where is satellite DNA typically found?
often found at centromeres
Minisatellite DNA
DNA repeats that are transcriptionally inactive
Telomeric DNA
6-base-pair repeats (15kb total) in telomeres
What sequence is typically associated with telomeric DNA?
TTAGGG
What is the role of telomeric DNA?
chromosome integrity
Hypervariable DNA
short repeats of core sequence that differ in numberof repeats
What is an example of hypervariable DNA?
Fingerprinting
Microsatellite DNA
2, 3, 4- base pair repeats that are not in a coding region
If microsatellite DNA is found within the coding region, what is it associated with?
associated with disease phenotype
How does microsatellite DNA insert itself into the coding region?
through slipped strand mispairing
What percentage of the human genome is made up of short interspersed nuclear elements (SINES)?
5% of the human genome
Transposon
DNA that can move through the chromosome
What are the functions of transposons?
Genetic variation
Alter gene expression
What percent of the human genome is made up of long interspersed nuclear elements (LINES)?
5% of the human genome
What is the central dogma of biology?
DNA → RNA ≤≥ Protein
DNA helicase
separates DNA double helix
Replication Fork
y-shaped structure where DNA replication occurs
DNA polymerase
enzyme replicating DNA
Leading Strand
continuous strand
Lagging Strand
synthesized in Okazaki fragments
DNA ligase
joins the DNA fragments
Semiconservative
only one strand is from original parent
Replication Bubble
point where DNA replication occurs in both directions
Where does transcription begin?
at the TATA box
Promoter
Where RNA polymerase binds
Where is the promoter sequence located?
upstream (5’) of the gene
What is important for regulation of gene expression
the promoter sequence
What enzyme transcribes DNA to RNA?
RNA polymerase
In what direction does RNA polymerase build RNA molecules?
in the 5’ to 3’ direction
What enzyme generates mRNA?
RNA polymerase
The template strand is also called the …
A. Antisense strand
B. Sense strand
A. Antisense strand
mRNA is a copy of which strand?
A. Antisense strand
B. Sense strand
B. Sense strand
What signals for the end of transcription?
polyadenylation signal
When the polyadenylation signal is reached, what is released?
the RNA polymerase
When does RNA processing occur?
before leaving the nucleus
What are the three steps of RNA processing?
Polyadenylation
5’ capping
mRNA splicing
Polyadenylation
200 adenylate residues that increase stability and prevent degradation
What is the role of polyadenylation?
nuclear export and translation
5’ Capping
guanine is added to the 5’ end of RNA transcript
Methyltransferase
enzyme that add methyl on the 5’ guanine at the N7 position
What is the role of the 5’ capping?
to transport mRNA to cytoplasm and to protect RNA transcript from degradation
mRNA Splicing
when the introns are excised, and exons are re-connected
What is the role of mRNA splicing?
prepares gene for translation
Note
Flashcard