Chapter 2 - Genes and Genetic Diseases Flashcards
What are chromosomes made of?
one long DNA molecule
What are the functional regions of DNA?
genes
DNA is a ____________ model
double-helix
How many protein coding genes do humans have?
20 000
What are the two strands in DNA held together by?
hydrogen bonds
What makes up the “backbone” of DNA?
deoxyribose-phosphate molecules
What makes up the “rungs” of a DNA molecule?
nitrogen bases
Adenine pairs with ______
Thymine
Guanine pairs with ______
Cytosine
Antiparallel
DNA strands run in opposite directions but parallel to one another
What is the purpose of the antiparallel nature of DNA?
one strand serves as a template for the creation of the second strand
Negative strand is a template for making the ________ strand
positive
Positive strand is a template for making the _________ strand
negative
Where is the parent strand broken to begin replicating?
replication fork
Nucleotide
building block of DNA and RNA composed of a sugar, nitrogen base, phosphate group
What is the result of DNA replication?
two identical copies of original DNA
What is a codon?
a pairing of 3 sequential nitrogen bases that code for a specific amino acid
How many types of amino acids does the body contain?
20
What makes up a protein?
a specific combination of amino acids
What is transcription?
when DNA gene sequence is copied to make an mRNA molecule
What is translation?
decoding of mRNA into amino acids to create proteins
What organelle translates proteins?
ribosomes
What is the primary end product of translation?
enzymes
What is RNA called when it moves out of the nucleus? Where does it go?
It is called mRNA and it goes to the ribosomes
What does the “m” in mRNA stand for?
messenger
What does mRNA deliver to the ribosome?
the “recipe” for making new proteins
What does transfer RNA (tRNA) do?
transport anticodon amino acids to ribosomes
What is a polypeptide chain?
a protein chain of anticodons
What ends the process of translation?
stop codon on mRNA
Transcription occurs (in/out) of the nucleus.
in
Translation occurs (in/out) of the nucleus.
out, in ribosomes
Genes
segments of DNA that encode for specific proteins
DNA
composed of various genes
Chromosomes
structure that organizes DNA into various sections
Genetics
the study of genes (how they carry, express, replicate information)
What is the result of mitosis?
two genetically identical (2n) daughter cells
What is the result of meiosis?
four genetically unique (n) daughter cells
When do genetic mutations occur?
during DNA replication
Substitution Mutation
incorrect amino acid sequence
What does substitution mutation result in?
a new amino acid
What is an example of the result of a substitution mutation?
sickle-cell anemia
Insertion Mutation
insertion of a new incorrect nucleotide
What does an insertion mutation result in?
multiple new amino acids
Deletion Mutation
the appropriate nucleotide is removed
What does deletion mutation result in?
multiple new amino acids
What is an example of the result of a deletion mutation?
cystic fibrosis
Mutation involves _______
evolution
When a mutation provides no benefit to the environment it means…
no evolution has occurred
When a mutation has negative effects on an environment it means…
extinction has occurred
When a mutation has a positive benefit in an environment it means…
that mutation has become dominant in the environment
What is a base pair substitution mutation?
Mutation where one base pair replaces another, only one amino acid changes
What are the two types of base pair substitutions?
missense and nonsense
Missense Base Pair Substitution
produces a change in a single amino acid
Nonsense Base Pair Substitution (think: “stop this nonsense!)
produces one of three STOP codons
What is a frameshift mutation?
the insertion or deletion of one or more base pairs
How much does a frameshift mutation alter an amino acid sequence?
greatly, produces dramatic change to the produced protein
Genotype
genetic material passes between generations
Phenotype
observable characteristics or traits of an organism
What does ‘autosomal’ mean?
the gene is located on the numbered (non-sex) chromosomes
Autosomal Dominant Inheritance
-located on numbered chromosomes
-single copy of mutation is enough to cause disease
Autosomal Dominant Inheritance Example:
father (Aa) with one copy of the abnormal gene produces 2/4 affected children
Autosomal Recessive Inheritance
-located on numbered chromosomes
-two copies of mutation required to cause disease
Autosomal Recessive Inheritance Example:
unaffected carrier mother and father (Aa) have four children: one is unaffected (AA), two are carriers (Aa), one is affected (aa)
Who carries an X-linked genetic mutation?
mother
X-Linked Mutations are present on which chromosomes?
sex chromosome
How does an X-linked mutation affect female children?
they become carriers
How does an X-linked mutation affect male children?
they become affected
Polygenic Traits
traits affected by more than one gene (ie. hair colour)
