DNA/PROTEIN SYNTHESIS Flashcards
what are the components of DNA
made up of nucleotides
what are the components of RNA
nucleotides
what is the function of RNA
decode messages from DNA
what enzymes are involved in DNA replication
helicase, DNA polymerase
what did Rosalin Franklin discover? what methods did she use
double helix in DNA, used x-rays
what is transcription
- RNA molecules are produced by copying part of a nucleotide sequence of DNA into a complementary sequence in RNA
- during transcription, RNA polymerase binds to DNA and separates the DNA strands
- RNA polymerase then uses one strand of DNA as a template from which nucleotides are assembled into a strand of DNA
What are Chargaff’s rules?
- the percentages of guanine (G) and cytosine (C) bases are almost equal in any sample of DNA
- the percentages of adenine (A) and thymine (T) bases are almost equal in any sample of DNA
what can an error in DNA replication cause?
genetic mutation and disorders
Name three differences between DNA and RNA.
- in RNA, the sugar is ribose rather than deoxyribose
- RNA is single stranded
- different bases: RNA: A-U, C-G, (Uracil)
What are the rules of base pairing?
A-T, C-G
TCGGCAC
AGCCTG
Where are proteins produced?
cytoplasm
ATGCCCGGAT
TACGGGCCTA
what is the replication fork
site where separation and replication occur
What are the functions of mRNA?
mRNA/messenger RNA: encodes amino acid sequence in polypeptide, decodes the information in DNA
carries copies of instructions for assembling amino acids into proteins
What is the name for each nucleotide triplet that codes for amino acids?
codon
What are the 3 types of RNA?
mRNA, tRNA, rRNA
DNA replication:
- S phase of interphase
- before a cell divides, it replicates its DNA in a process called replication
- during DNA replication, the DNA molecule separates into two strands
- each strand of the double helix of DNA serves as a template for the new strand
transcription and translation.
Now DNA is used by cells
Now the instructions in DNA are read and followed
DNA is a recipe for protein (sequence of amino acids)
Messages in DNA are decoded by RNA
what are the functions of tRNA
tRNA/transfer RNA: brings amino acids to ribosomes during translation
during protein construction, tRNA transfers each amino acid to the ribosome
function of DNA polymerase
- principle enzyme involved in DNA replication
- joins individual nucleotides together produce a DNA molecule and then “proofreads” each new strand of DNA
INCOMPLETE DOMINANCE
Neither allele is dominant over the other
Heterozygous genotypes show an in-between phenotype
Heterozygotes will have a blend of traits
AKA intermediate inheritance
Example: snapdragon flower color
Homozygous: RR = red
Homozygous: rr = white
Heterozygous: Rr = pink
what enzyme is involved in transcription
RNA polymerase
components of nucleotide
monomer of nucleic acids, composed of five-carbon sugar (deoxyribose) a phosphate group, and a nitrogenous base.
how replication occurs
- dna is carried out by enzymes that “unzip” a molecule of DNA (helicase)
- hydrogen bonds between the base pairs are broken and the two strands of DNA unwind
what is translation
Translation is the decoding of an mRNA message into a polypeptide chain
Translation takes place on ribosomes
During translation, the cell uses information from messenger RNA to produce proteins
The ribosome binds new tRNA molecules and amino acids as it moves along the mRNA
The process continues until the ribosome reaches a stop codon
extra:
Each tRNA molecule carries only one kind of amino acid
In addition to amino acids, each tRNA molecule has three unpaired bases
These bases, called anticodon, are complementary to one mRNA codon
process:
BEGINS when a mRNA molecule attaches to a ribosome
As each codon of the mRNA molecules moves through the ribosome, the proper amino acid is brought into the ribosome by tRNA
In the ribosome, the amino acid is transferred to the growing polypeptide chain
where does transcription occur
nucleus
where does translation occur
on ribosomes in the cytoplasm
mendelian dominance
One allele is dominant over the other
Heterozygotes show the dominant phenotype
Example: pea plant flower color:
PP = purple
Pp = purple
pp = white
POLYGENIC INHERITANCE
Whenever multiple genes affect a characteristic, the variation of phenotypes within a population can become even greater
When teo or more genes affect a single character, it is called Polygenic inheritance
Examples:
Eye color (8 different genes)
Height
Skin color (over 150 genes)
Hair color
codominance
Neither allele is dominant over the other
Heterozygous genotypes show both alleles
Example: blood type in humans
BLOOD TYPES IN HUMANS
Letters in blood types relate to proteins attached to red blood cells
Type A blood has A antigens (proteins that tell your immune system that you are you) on RBC → blood/plasma contains Anti-B antibodies
Type B blood has B antigens on RBC → blood/plasma contains Anti-A antibodies
Type AB blood has A and B antigens on RBC → no anti A or Anti B antibodies
Type O blood has neither A or B antigens (Naked) → blood/plasma contains anti-A and anti-B antibodies
Type A blood can be noted as I^A I^A or I^A i
Type B blood can be noted as I^B I^B or I^B i
Type AB can be noted as I^A I^B
GREGOR JOHANN MENDEL (1822-1884)
Father of genetics
What is genetics: Field of biology devoted to understanding how characteristics are transmitted from parents to offspring
Mendel observed 7 characteristics
A characteristic is a heritable feature, such as flower color
Each characteristic occurred in 2 contrasting traits
A trait is a genetically determined variant of a characteristic, such as yellow flower color
Mendel’s experiments
The P generation → F1 generation → F2 generation
Mendel hypothesis
Something within the pea plants controlled the characteristics
Called these controls factors (now known as alleles)
Each trait was inherited by means of a separate factor
A pair of alleles/factors controlled each trait
law of independent assortment
Multiple factors separate independently of one another during the formation of gametes
Traits produced by dominant factors do not necessarily appear together
Factors for individual characteristics are not connected
law of segregation
A pair of factors is segregated/separated during the formation of gametes
Paired factors separate during the formation of reproductive cells
Each gamete receives one factor of each pair
When two gametes combine during fertilization, the offspring will have two factors for each characteristic
HOW MANY ALLELES DO WE GET FROM OUR PARENTS
During meiosis, gametes receive ONE chromosome from each homologous pair of chromosomes
Thus, when the gametes combine in fertilization, the offspring receives from EACH parent ONE allele for a given trait
SEX DETERMINATION
Like homologous chromosomes, sex chromosomes also pair during meiosis I. as meiosis proceeds, the paired chromosomes separate and move to different cells. When an egg (always carries an X) is fertilized by a sperm cell (X and Y), the offspring will be either male or female
sex linked traits
Sex linked traits - a trait that is coded for by an allele located on a sex chromosome
An X chromosome is much larger than a Y chromosome so there are MORE X-linked than Y-Linked traits
Most X-linked traits have no homologous counterpart on the Y chromosome. In humans, the Y only contains the gene for “maleness”
Because males only have one X chromosome, a male who carries a recessive allele on the X will exhibit that X-linked trait
Example: colorblindness is an X-linked recessive trait, therefore most people who are colorblind are males
