Lecture 6

Question 1

Central Dogma

Answer 1

DNA–> transcription-> mRNA–>translation–> proteins

Question 2

Transcription:
Translation:

Answer 2

-DNA-directed synthesis of RNA
-Synthesis of polypeptides from RNA template

Question 3

Genetic code
codon: block of ___ RNA nucleotides corresponding to an amino acid
-there are ____ stop codons which are:
-start codon=
-code is degenerate=
-code practically _______

Answer 3

-3
-3; UAA, UAG, UGA
-AUG (amino acid= methionine)
-lots of different codons that carry the same amino acid
-universal

Question 4

Change in DNA (nucleic acid sequence) is _______
3 types are…

Answer 4

mutation
1. Insertion
2. Deletion
3. Substitution

Question 5

The cell cycle:
The cell cycle includes interphase and the mitotic phase

Interphase includes three subphrases:

Mitotic phase includes subphrases:

Answer 5

First gap phase (G1)
Synthesis phase (S)
Second gap phase (G2)

Prophase
Metaphase
Anaphase
Telophase
Cytokinesis

Question 6

G1 phase

Answer 6

cell growth and normal metabolic roles

Question 7

S phase

Answer 7

DNA replication

Question 8

G2 phase

Answer 8

more cell growth and preparation for mitosis

Question 9

Prophase

Answer 9

chromosomes condense and nuclear envelope breaks down, spindle fibers grow from centrioles and migrate to opposite pole

Question 10

Metaphase

Answer 10

chromosomes line up along midline (metaphase plate) and spindle fibers attach to kinetochores

Question 11

Anaphase

Answer 11

centromeres divide in two, spindle fibers pull sister chromatids to opposite poles of the cell

Question 12

Telophase

Answer 12

chromosomes gather at each pole of cell and decondense; new nuclear envelope appears at each pole (cleavage furrow appears in animal cells–> slitting of two new daughter cells)

Question 13

cells divide when:
-they have enough _____ for two daughter cells
-they have replicated their DNA
-they have adequate supply of ______
-they are simulated by ____________ (chemical signals)
-neighboring cells ____, opening up space

Answer 13

cytoplasm
nutrients
growth factors
die

Question 14

Cells stop dividing when:
-they snugly contact neighboring cells
-nutrients or growth factors are _______
-they undergo contact inhibition: _________

Answer 14

withdrawn
the cessation of cell division in response to contact with other cells

Question 15

Cancer:
unrestrained, uncontrolled growth of cells due to a failure of cell cycle control

-Two kinds of genes can disturb the cell cycle when they are MUTATED
1.
2.

Answer 15

1. tumor-suppressor genes
2. proto-oncogenes

Question 16

Tumor-suppressor genes

Answer 16

act like brakes to slow down damaging mutations
needs 2 damaged copies to cause cancer

Question 17

Proto-oncogenes

Answer 17

act like an accelerator to cause damage
only 1 copy must be damaged to cause cancer

Question 18

Principle of Independent Segregation

Answer 18

pairs of alleles are separated when gametes are formed

Question 19

Principle of independent assortment

Answer 19

Pairs of alleles will be sorted independently of one another
when gametes are formed

Question 20

Exceptions to Mendel’s Model
1. P____________
2. P____________
3. M__________
4. I______________
5. C_____________
6. E_____________
7. E_____________
8. S_____________

Answer 20

Polygenic inheritance
Pleiotropy
Multiple alleles
Incomplete dominance
Codominance
Environmental influence
Epistasis
Sex Linkage

Question 21

Polygenic inheritance:

Answer 21

more than one gene determine characteristic trait

Question 22

Pleiotropy:

Answer 22

one gene affects multiple different traits
-e.g. albinos, sickle cell anemia, cystic fibrosis

Question 23

Multiple alleles:

Answer 23

multiple alleles present to form genes
e.g.: blood type and height

Question 24

Codominance:

Answer 24

two versions of alleles of same gene are expressed separately to yield a different trait
-Red (RR) + White (rr)= Red & White (Rr)

Question 25

Environmental influence

Answer 25

genes can change due to environment
e.g: temp in siamese cats and color of fur
carcinogens can cause mutation in genes

Question 26

Sex-linked genes:

Answer 26

genes located on the sex chromosomes
-color blindness: found on Y chromosome

Question 27

Epistasis:

Answer 27

above the genome
-suppression of genes can occur over time