Central Dogma and Mutations

Ch. 1 and 2

Human 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?

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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?

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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

\n

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

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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

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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 …

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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