Chapter 4: Genes Flashcards
what is genetics?
the study of heredity
what is heredity?
passing on characteristics (traits) from parents to offspring so offspring resemble parents and eachother
list 4 microbial traits
- ) shape and structure (morphology)
- ) biochemical reactions (metabolism)
- ) movement and behavior
- ) interactions with other organisms (pathogenesis)
what is phenotype?
actual, expressed properties or characteristics (traits)
what is genotype?
organisms genetic makeup (total collection of genes)
what is genome?
- total genetic makeup in cell (can mean genotype)
- all the cells DNA
- all viruses’ DNA or RNA
what is environment?
any factor affecting the expression of a phenotype other than genes
__________+_________—>___________-
genotype + environment–>phenotype
the functional unit of genetic information is the _____
gene
describe what genes are the 4 things they encode for
Segment of DNA in cells (or either RNA or DNA in viruses) which contained the coded information that determines:
- ) the sequence of mRNA which determines the primary structure of a given polypeptide (coding or structural genes)
- ) the sequence for rRNA (ribosomal RNA genes)
- ) the sequence for tRNA (transfer RNA)
- ) the sequence of regular RNA
are genes in cells single stranded DNA or double stranded
double stranded (ds) DNA
what is the flow of biological information
Genes (genotype)–> mRNA and other RNA–> polypeptide primary sequence–>proteins (enzymes)–> regulates cell chemistry–>determines cell/viral morphology and physiology (phenotype)
(slide 7)
DNA is a polymer of what?
RNA is a polymer of what?
what links these together?
DNA-deoxyribonucleotides
RNA-ribonucleotides
phosphodiester bonds
DNA and RNA differ in (2 things)
the nitrogenous bases they contain
the sugars they contain
describe DNA structure (6)
-polymer is deoxyribonucleotides
-bases are adenine, guanine, cytosine, and thymine
-sugar is deoxyribose
-adenine (purine) and thymine (pyrimidine) pair by 2 hydrogen bonds
-guanine (purine) and cytosine (pyrimidine) pair by 3 hydrogen bonds
-in all cells, DNA molecule is a double stranded helix
(slides 14-17; 17 is a video)
slide 13
information about DNA length
describe RNA structure (5)
- polymer is ribonucleotides
- sugar is ribose
- bases are adenine, guanine, cytosine, and uracil
- phosphodiester bonds
- In cells, Most RNA molecules are single stranded; some double stranded or have double strand regions
Three different types of RNA exist which may differ from each other in function, site of synthesis, and in structure. What are they?
messenger RNA (mRNA) ribosomal RNA (rRNA) transfer RNA (tRNA)
describe viral genomes (8)
- Either DNA or RNA in same virus particle, not both
- DNA or RNA can be single stranded (ss) or double stranded (ds)
- Viral nucleic acid had very little or no protein associated with it
- Viral nucleic acid can be linear or circular
- Viral genomes may consist of 1 piece of nucleic acid or several (ie, Influenza virus had 8 pieces ss RNA)
- Most viral genomes have between about 20 and 100 genes (some larger exceptions)
- Viral genomes consist of between 20,000 and 100,000 nucleotides
- Viral genomes are packed within a protein coat called the capsid
describe prokaryotic genomes (7)
- Always composed of ds DNA
- ds DNA has only a little protein associated with it
- Bacterial chromosome is about 98% ds DNA and 2% protein
- Most DNA is circular and supercoiled; some linear
- Most have a single piece of DNA as their bacterial chromosome; but some have 2 or more
- Prokaryotes have between about 2000 – 5000 genes
- Prokaryote genomes are between 2 million and 5 million nucleotides
what are plasmids? about how many genes?
- Small pieces of open circular ds DNA in the cytoplasm
- Found in many prokaryotes; between 5 – 50 genes
slides 23 and 24
pictures of super coiled DNA
describe eukaryotic genomes (6)
- Always composed of ds DNA
- Mostly linear; some circular
- DNA spread over many eukaryotic chromosomes
- Most eukaryotes have several chromosomes
- All members of same species have same number of chromosomes (called species number or chromosome number)
- Eukaryotic chromosomes are structures for organizing a lot of DNA in a little volume
each eukaryotic chromosome consists of (3 things)
- ) 34-35% ds DNA
- ) ~1% RNA
- ) 64-65% proteins (histones and non histones)
Eukaryotic chromosomes can exist in several types of packing. Describe (2)
-During non dividing times (interphase), they are the most loosely packed (decondensed); at this time, the individual chromosomes exist but are not visible and they are referred to as chromatin
-During mitosis or meiosis, the chromosomes condense and become more tightly packed; they are also visible as individual chromosomes at this time
(slide 28)
what are the 5 levels or eukaryotic chromosome structure?
1.) ds (naked) DNA- 2nm
2.) nucleosomes- 10nm (held together by histone proteins)
3.) solenoids- 30nm (held together by histone and non histone proteins)
4.) 300nm fibers- supercoils (held together by non histone proteins)
5.) higher levels- only occur during cell division
(slide 30 and 31)
what is DNA replication? (2)
-Complex process involving numerous proteins which help ensure accuracy
-The 2 strands separate, each serving as a template for synthesis of a complementary strand
(slides 33 and 34; 34 is video)
slides 35-39
35: weird information to make into card; look at
36: picture
37: video
38: more weird info to make into card
39: table
name and describe the 5 materials required for DNA synthesis/replication
slides 40-42
describe DNA replication
44-47 and in purple notebook
describe replication machinery (2)
- DNA polymerase catalyzes synthesis of complementary strand of DNA
- DNA synthesis in 5’ to 3’ direction forming phosphodiester bonds
replication machinery enzymes require what 3 things?
- ) a template – directs synthesis of complementary strand
- ) a primer – DNA or RNA strand
- ) dNTPs (dATP, DTTP, DCTP, dGTP) – deoxynucleotide triphosphates
slide 51
E. Coli replication?
describe DNA gyrase (2)
- topoisomerase
- also introduces negative supercoiling to help compact bacterial chromosome
describe primase
synthesizes short complementary strands of RNA (~10 nucleotides) to serve as primers needed by DNA polymerase
DNA ligase forms a ________________ between 3’-_________ of the growing strand and the 5’-_________ of an Okazaki fragment
phosphodiester bond; hydroxyl;phosphate
slide 54-56
describe proofreading (3)
-Carried out by DNA polymerase III
-Removal of mismatched base from 3’ end of growing strand by exonuclease activity of enzyme
-This activity is not 100% efficient
(57-58)
slide 59
E Coli?
Telomerase is an enzyme found in eukaryotes that can do what?
synthesize DNA using an RNA template and an internal RNA template thus solving the “end” replication problem
describe the end replication problem and how this is solved in euks and bacteria
-shortening of chromosomes after each round of replication
-solved in eukaryotes by telomerase enzyme
-solved in bacteria by disguising the ends of the linear chromosome
(61-62)
describe accuracy of DNA replication
last slide :)
