Genetics Part III

Question 1

definition of a MUTATION

Answer 1

MUTATION:
- permanent change within the NUCLEOTIDE SEQUENCE of the GENOME of an ORGANISM

RESULTS:
- begin to see GENETIC VARIABILITY–impacts VIABILITY, FUNCTION, and PATHOGENICITY
- essential to NATURAL SELECTION
(not all mutations are bad–lets EVOLUTION occur)
- occurs at RANDOM in NATURE

Question 2

describe ANTIBIOTIC RESISTANCE

Answer 2

an example of MUTATIONS that begin to INCREASE BACTERIA and the MICROBE’s RESISTANCE towards ANTIBIOTICS
- reason for why we need to continue ANTIBIOTIC TREATMENT–allows to kill the FULL RANGE OF BACTERIA (despite their RESISTANCE LEVELS)

Question 3

what are the CHROMOSOMAL MUTATIONS?

Answer 3

• DELETION
• DUPLICATION
• INVERSION
• TRANSLOCATION

Question 4

Down’s Syndrome

Answer 4

DUPLICATION MUTATION (TRISOMY)–CHROMOSOME 21:
- results in a WIDE RANGE of DEVELOPMENTAL DELAYS and PHYSICAL DISABILITIES
- around approx. HALF of PEOPLE with condition have a CONGENITAL HEART DEFECT
- DUPLICATION of around 500-800 GENES
- specific PHENOTYPE; mainly due to VARIABLE EXPRESSION of SUBSET of GENES

Question 5

CRI DU CHAT SYNDROME

Answer 5

DELETION IN CHROMOSOME 5:
- have MICROCEPHALY (weaker development of brain)
- WEAK MUSCLE TONE
- DELAYED DEVELOPMENT

Question 6

WOLF-HIRSCHHORN SYNDROME

Answer 6

DELETION IN CHROMOSOME 4:
- DELAYED DEVELOPMENT and INTELLECTUAL DISABILITY
- SEIZURES
- change within FACIAL CHARACTERISITICS

Question 7

JACOBSEN SYNDROME

Answer 7

DELETION in CHROMOSOME 11:
- has a VARIETY of SYMPTOMS
- has LEARNING DIFFICULTIES and COGNITIVE IMPAIRMENT
- has DISTINCTIVE FACIAL FEATURES

Question 8

definition of POINT and what are its TYPES?

Answer 8

change within a SINGLE BASE PAIR–BASE SUBSTITUTION
- can HAPPEN NATURALLY during replication of result of DNA DAMAGE and IMPROPER REPIAR

TYPES:
- MISENSE
- NONSENSE

Question 9

types of FRAMESHIFTS

Answer 9

• DELETIONS
• INSERTIONS

Question 10

does POINT MUTATIONS ALWAYS lead to changes within our PHENOTYPE? what are SILENT MUTATIONS? what are MISSENSE MUTATIONS?

Answer 10

NO!
- our GENETIC CODE is REDUNDANT
- not EVERY CHANGED NUCLEOTIDE necessarily will change the actual AMINO ACID SEQUENCE of the PROTEIN–this is considered a SILENT MUTATION

• if there is CHANGE in the SEQUENCE and results in a CHANGE within the AMINO ACID SEQUENCE–this is considered a MISSENSE MUTATION; and EVEN THEN!! they don’t always translate to phenotypic or functional changes

Question 11

what is a NEURAL MUTATION?

Answer 11

type of MISSENSE MUTATION that ALTERS the AMINO ACID SEQUENCE of the PROTEIN
- but DOES NOT CHANGE FUNCTION
- typicaly when the ONE AMINO ACID REPLACED by a CHEMICALLY SIMILAR ONE or just has LITTLE INFLUENCE on PROTEIN FUNCTION

Question 12

sickle cell anemia

Answer 12

single change within the GLOBIN GENE

Question 13

definition of a NONSENSE MUTATION

Answer 13

CHANGE in the SEQUENCE that introduces a STOP CODON–STOPS TRANSLATION

Question 14

definition of FRAME SHIFT MUTATIONS

Answer 14

mutations that occur when NUCLEOTIDES are EITHER INSERTED or DELETED from the DNA SEQUENCE
- have PRETTY SEVERE EFFECTS–can begin to EFFECT ALL AMINO ACIDS DOWNSTREAM of the INSERTION
- can result in INTRODUCTION of STOP CODON and EARLY STOP of TRANSLATION
- PROTEINS cannot be PROPERLY SYNTHESIZED and have PROPER FUNCTION

Question 15

define MUTAGENS + describe NUCLEOTIDE ANALOGS

Answer 15

CHEMICAL MUTAGENS:
- causes a SPECIFIC BASE CHANGE

NUCLEOTIDE ANALOGS:
- similar to the NITROGENOUS BASES but with SLIGHTLY DIFFERENT BASE PAIRING
- if present during growth = can cause MISTAKES during REPLICATION
- can cause SMALL DELETIONS and INSERTIONS–making FRAME-SHIFT MUTATIONS

Question 16

what are our types of MUTAGENS (2)?

Answer 16

RADIATION:
(X RAYS and GAMMA RAYS)
- releases ELECTRIONS and begins to BOMBARD SURROUNDING CELLS and can cause damage to DNA MOLECULES

UV RADIATION:
- causes DNA DAMAGE by causing the FORMATION of COVALENT BOND between 2 ADJACENT THYMINE’S within DNA

Question 17

what is the RATE of MUTAGENESIS?

Answer 17

MISTAKES:
occurs during REPLICATION with RATE of 1 in 1 BILLION per BASE PAIR

**all depends on HOW BIG A GENE IS
- 1000 bp gene = 1 in a million
- BIGGER GENE, MORE CHANCE OF ERRORS

CHEMICAL MUTAGENS:
- can increase RATE OF MUTAGENSIS by 10-1000x (rate of 1 in 1000)

Question 18

how can we IDENTIFY MUTATIONS?

Answer 18

can be DETECTED by SELECTING for an ALTERED PHENOTYPE

POSITIVE SELECTION:
- mutation results in a GAIN OF FUNCTION that can be DIRECTLY SELECTED FOR

INDIRECT SELECTION:
- where the MUTATION RESULTS in a LOSS OF FUNCTION–screening COLONIES for DESIRED PHENOTYPE

Question 19

definition of CARCINOGENS

Answer 19

• many known MUTAGENS can cause CANCER
• can use BACTERIA to determine if something if MUTAGENIC–most likely CARCINOGENIC
• use of the AMES TEST

Question 20

what are our TYPES of GENETIC TRANSFERS?

Answer 20

VERTICAL:
- parent to child

HORIZONTAL:
- passing GENES between MICROBES
- occuts in less than 1% of POPULATION

Question 21

what are our TYPES OF HORIZONTAL GENE TRANSFERS?

Answer 21

• TRANSFORMATION
  *NATURAL
  *CHEMICAL COMPETENCE
• CONJUGATION
• TRANSDUCTION

Question 22

definition of TRANSFORMATION

Answer 22

• derived from experiment; DNA transferred from the DEAD ENCAPSULATED STRAIN to the NON-ENCAPSULATED STRAIN (now BECAME VIRULENT)
• can make the bacteria CHEMICALLY COMPETENT

BACTERIAL SPECIES:
- bacillus
- haemolphilus
- niseeria
- streptococcus
- staphylococcus

Question 23

definition of CONJUGATION

Answer 23

• MEDIATED by a PLASMID
  (PLASMIDS–small independently replicating SMALL CIRCULAR DNA
• uses DIRECT CELL-To-CELL CONTACT
• requires DIFFERENT MATING TYPES;
  DONOR–carries a SPECIFIC PLASMID with GENES that encode for a SEX PILI
• RECIPENT CELLS DO NOT HAVE PLASMID

Question 24

definition of TRANSDUCTION

Answer 24

the TRANSFER of DNA from DONOR CELL to RECIPENT CELL inside a VIRUS that INFECTS the BACTERIA
- known as BACTERIOPHAGES; viruses that infect bacteria
- can sometimes package and move BACTERIA’S CHROMOSOMAL DNA and make their own PHAGE DNA

Question 25

definition of PLASMIDS

Answer 25

genetic elements that provide a MECHANISM for MOVING GENETIC MATERIAL between BACTERIA
- small independently REPLICATING SMALL CIRCULAR DNA
- non-essential

TYPES:
- FERTILITY PLASMIDS
- RESISTANCE PLASMIDS
- VIRULENCE PLASMIDS