ch. 9 Flashcards
Genetics
the study of heredity
Differences b/w human and bacteria genetics
- genetic diversity is not established in binary fusion
- Bacteria divide by binary fusion or mitosis
100% identical genome of parent to daughter, as long as no mutation occured
genome
sum total of genetic material of an organism
Where do genome appear in non-chromosomal sites? (#3)
mitochondria
chloroplasts
plasmids
Genome of cells - do they contain DNA or RNA?
DNA
Genome of viruses - do they contain DNA or RNA?
BOTH
DNA OR RNA
chromosome
discrete cellular structure composed of a neatly packaged DNA molecule
Where are eukaryotic chromosomes located? How many and shape?
located in the nucleus
multiple and linear
Bacterial chromosomes. How many and shape?
single circular loop
What are chromosomes subdivided into?
genes
Define genes
the fundamental unit of heredity responsible for a given trait
Genes function
- provides information for a certain cell function
- segment of DNA that contains the necessary code to make a protein or RNA molecule
GENE LOCATION
SITE ON THE CHROMOSOME
What are the three basic categories of genes?
- genes that code for proteins - structural genes
- genes that code for RNA
- genes that control gene expression - regulatory genes
Define genotype
all types of genes constitute the genetic makeup
Define phenotype
- the expression of the genotype creates observable traits
- what can you see - but not as accurate for bacteria
- physical traits with microscope or staining
How are DNA molecule compacted in the cell?
supercoils or superhelices
In prokaryotes, by the action of the enzyme DNA gyrase - function?
makes and unknot
prevents DNA knot coils
In eukaryotes packaging is more complex. Describe packaging
three or more levels of coiling, starting with a chain of nucleosome (DNA around histone proteins)
PURINE
Adenine and Guanine
Pyrimidines
Cytosine and Thymine
Replication occurs on both strands _________
simultaneously
Describe the semiconservative process
- the parent DNA molecule is uncoiled
- The two strands are separated exposing the nucleotide sequence to serve as templates
- two new complementary strands are synthesized by using each single-stranded template as pattern
All chromosomes have a specific origin of replication T OR F?
TRUE
Define origin of replication
site as the place where replication is AT-rich, thus less energy is required to separate the two strands
how many replication forks?
2
Define replication forks
where new DNA is being synthesized, each containing its own set of replication enzymes
Helicase function
unwinds and unzips the DNA double helix
DNA polymerase III
adds DNA nucleotides to make daughter strand
making an exact duplicate of the DNA requires how many different enzymes?
30 different enzymes
Where is RNA primer synthesized?
at the origin of replication by a primase
DNA polymerase III direction of synthesis
adds nucleotides in a 5’ to 3’ direction
Leading strand - direction it is synthesized?
continuously in 5’ to 3’ direction
Lagging strand - direction it is synthesized?
synthesized 5’ to 3’ in short segments; overall direction is 3’ to 5’
DNA polymerase I function
removes the RNA primers and replaces them with DNA
what is transcription?
genetic information in DNA molecules is conveyed to RNA through the process of transcription
What is translation?
the information contained in the RNA molecule is then used to produce proteins in the process of translation
A wide variety of specialized RNAs act by regulating gene function such as
tRNA
mRNA
rRNA
each structural gene is an ordered sequence of nucleotides that codes for a protein’s ______ ______
primary structure
Groups of three consecutive bases, ________ or _______, on one DNA strand are transcribed into RNA sequence triplets
triplets or codons
Each triplet of nucleotides on the RNA specifies a particular ___ ___
amino acid
A protein’s primary structure (chain of amino acids) determines
shape and function
Proteins contribute to the cell phenotype as ______ and ________
enzymes and structural proteins
The general structure of the ribonucleic acid (RNA) is different than that of the DNA molecule in several ways:
list them (3)
- RNA is single-stranded molecule that can assume secondary and tertiary levels of complexity, leading to specialized forms of RNA (mRNA, tRNA, and rRNA)
- RNA contains uracil (U), no thymine (T) like DNA, as the complementary base-pairing mate for adenine (A)
- The sugar in RNA is ribose rather than deoxyribose
messenger mrna contain codes for
sequence of amino acids in proteins
mRNA function
carries the DNA master code to the ribosomes
Is mRNA translated?
yes
tRNA contains codes for
specifying a given amino acid
function of tRNA
carries amino acids to ribosomes during translation
Is tRNA translated?
NO
(ribosomal) rRNA contains codes for
forms the major part of ribosomes and participates in protein synthesis
Is rRNA translated?
no
primer contains codes for
an RNA that can begin DNA replication
function of primer
primes DNA
Is primer translated?
no