Lectures 5 and 6 Flashcards
What is the study of genetics?
Studies how physical traits and diseases pass form generation to generation
What are genes?
They are the physical units of heredity
They are the basic structural and functional unit of genetics
Genes are made up of DNA
Do we all have two copies of each gene?
Yes
One from each parent
Are most genes the same in all people?
Yes
<1% are slightly different between us
What is a gene physically?
It is a string of chemical building blocks or nucleotides in a DNA molecule
How many different nucleotides are there in DNA?
4
Each nucleotide is a letter
What do nucleotides do?
They store information in the form of a genetic code
What does a series of nucleotides form?
Amino acids
Chain of those make up polypeptides
What is an allele?
An allele is a gene
It was previously used to describe variant forms of a gene
An allele is one of a number of alternate forms of the same gene
What can different alleles result in?
Can result in different phenotypes, such as eye pigmentation
Most genetic variations result in little or no observable variation
What is a wild type allele?
It is a normal allele, as opposed to a mutant gene or allele
What is the scientific name for DNA?
Deoxyribonucleic acid
What is DNA?
It is the genetic code that determines all the characteristics of a living thing
What is DNA made of?
Nucleotides
What does each nucleotide comprise of?
A sugar, a phosphate molecule, and a base
How many genes does DNA contain?
Thousands
What is at the end of each chromosome?
Telomeres
They protect the ends of the chromosomes during DNA replication (plastic tip on shoelace)
What do telomeres consist of?
Repeats of DNA sequences associated with proteins
What happens to telomeres over time and many replications?
It becomes shorter and shorter
This is due to the fact that the DNA strand is unable to replicate itself to the very end
How do telomeres protect the chromosome?
The repetitive sequence of telomeres lacks information for protein synthesis, thus protects the genes that are in more internal regions of the chromosomes
What happens when the telomere gets too short?
The integrity of the genes is compromised and no longer divides
The condition or process of deterioration with age
May explain the functional decline of most body organs
What do chromosomes consist of?
Single long molecule of double stranded DNA
Typically in homologous pairs
One maternal and one paternal
How many pairs of chromosomes do humans have?
23
How are chromosomes made?
A single length of DNA is wrapped many times around lots of proteins called histones, to form structures called nucleosomes
These nucleosomes then coil up tightly to create chromatin loops
The chromatin loops are then wrapped around each other to make a full chromosome
What is the short arm of a chromsome?
p
What is the long arm of a chromosome?
q
What is holding both sides together?
Centromere
What are histones?
Proteins
What are chromatin loops similar to?
Thread
And the chromosome is the yarn
What is a genotype?
Genetic makeup of an organism
The sum of genes transmitted from parent to offspring
What is a phenotype?
Manifestation of genes
Anatomical and behavioral traits from both heredity and the environment
What you can see
What is a karyotype?
The entire set of 46 chromosomes
Looks at all of the chromosomes and any abnormality with them
What are proteins a product of?
Genes
DNA controls the kind of and amounts of proteins present in cells
Phenotypes are controlled by proteins
Does each gene code for multiple proteins?
Yes
Humans contain about 20,000 to 25,000 genes that specify between 100,000 and 200,000 proteins
What are proteins made of?
Amino acids
How many essential amino acids are there?
20
10 made in our bodies and 10 we need in our diet
Each amino acid has what? (3)
Animo group
Carboxyl group
R group
What is the R group of an amino acid?
It is a term used to indicate the position of an unspecified group in a chemical structure
Side chains that are different for each amino acid
What is special about Tyrosine (amino acid)?
Only produced by phenylalanine (produced outside the body)
You need to consume phenylalanine to produce Tyrosine
How are amino acids linked together?
Covalent peptide bonds
Formed between the amino group and the carboxyl group
What do two linked amino acids form?
A dipeptide
What do three amino acids form?
A tripeptide
What do 10 or more amino acids form?
A polypeptide
What happens when the carboxyl group bonds with the amino group to form a polypeptide?
It releases a molecule of water
Why are covalent bonds used for polypeptides?
Because they are very strong
They keep the electrons stable
How is the sequence of amino acids determined for a protein?
Determined by the bases in the gene encoding that protein
Proteins contain within their amino acid sequences the necessary information to determine what?
How that protein will fold into a three-dimensional structure
The stability of the resulting structure
What happens if the code is read incorrectly?
The protein will be wrong
It won’t do what it was supposed to do
Is DNA the hereditary transmission molecule in gametes?
Yes
What are the two primary functions of DNA?
To duplicate itself
To control the development of the rest of the cell in a specific manner
What is a nucleotide?
Single building block of DNA
Consists of a deoxyribose sugar, a phosphate group, and a nitrogenous base
What are the bases in DNA?
Adenine
Guanine
Cytosine
Thymine
What bases pair together in DNA?
A and T
C and G
Which bases are purines (two ring structure)?
A and G
Which bases are pyrimidines (one ring structure)?
C and T
What are pentoses?
The sugar in nucleic acids, contain 5 carbon atoms
What is the sugar called in DNA?
Deoxyribose
What is the sugar called in RNA?
Ribose
What is the difference between deoxyribose and ribose?
A single oxygen atom that is absent (deoxy) in deoxyribose but present in ribose
What is present at the 5’ position?
A phosphate molecule