Biology Class 3 Flashcards Preview

Psych/Soc > Biology Class 3 > Flashcards

Flashcards in Biology Class 3 Deck (57)
Loading flashcards...
1

Nucleoside vs nucleotide

nucleoside includes just the sugar and base, while nucleotide also includes the phosphates

2

Bond formed between two nucleotides

phosphodiester bond

3

Monomer of nucleic acids

Nucleotides/nucleosides

4

Important facts about nucleic acids

1. 5'-3' synthesis
2. Antiparallel & complementary
3. Phosphodiester bond

5

Pyrimidine vs Purine

Pyrimidine: Cytosine, thymine, uracil
- 6 C ring
Purine: Adenine & Guanine
- 6 C & 5 C ring

6

Bases in DNA vs RNA

DNA: Adenine, guanine, cytosine, thymine

RNA: Adenine, guanine, cytosine, uracil

7

How many H bonds hold a AT bond vs GC bond

2, 3 respectively

U pairs with A

8

Genome

All the DNA in an organism

9

Genome: Prokaryotes vs Eukaryotes

Prokaryote: one singular circular DNA genome
Eukaryote: 23 pairs of linear chromosomes (46 chromosomes)

10

How is the Prokaryote genome protected?

1. Methylation - methylates chromosome to protect from own RE
2. Supercoiling - Gyrase helps with supercoiling and helps compact the chromosome

11

How do Eukaryotes form chromosomes?

1. DNA is wrapped around 8 histone molecules & forms a nucleosome
2. Condenses to form chromatin
3. Further condenses to form chromosome

12

Euchromatin vs Heterochromatin

Euchromatin
- unwound, active, light staining

Heterochromatin
- wound, inactive, dark staining

13

Centrosome

Region of the chromosome
- attaches spindle fibers
- connects sister chromatids after replications

14

Telomeres

1. End of chromosomes
2. Short sequence repeats
3. Allows ends of chromosomes to loop around & bp with itself and allows it to stabilize the chromosome

15

Central Dogma

DNA (transcription) --> RNA (translation) --> Protein

16

What are the stop and start codons

Start: AUG (Met)
Stop: UAG,UAA,UGA

17

Human Genome

1. 46 chromosomes
2. ~21,000 genes
3. 3 billion nucleotidesLarge intergenic regions (regions that don't code for proteins)

18

Different types of point mutations

Missence- codon for aa becomes new codon for new aa (effect: change aa)

Nonsense: codon for aa becomes STOP codon (effect: shortened protein)

Silent: Codon for aa becomes new codon for same aa (effect: no effect)

19

Sources of Mutations

Polymerase Errors
Endogenous damage (a. ROS b. Physical Damage)
Exogenous Damage (a. radiation b. chemicals)
Transposons

20

Polymerase Errors

1. Point mutations
2. Small repeats
3. Insertions/deletions (small, frameshift)

21

Endogenous Damage

1. Oxidized DNA
2. Cross-linked bases
3, Double or single stranded breaks

22

Exogenous Damage

1. UV radiation (pyrimidine dimers T-T or T-C)
-> usually repaired by direct reversal by white light
2. X-Rays = double stranded breaks & translocations
3. Chemicals = can lead to physical damage or to intercalation (insertion of molecules into bases of DNA)

23

Transposons

1. Insertions/deletions (large)
2. Inversions
3. Duplications

24

Transposon Structure

Inverted repeats on both sides with transposae in center

25

Transposase

enzyme that cuts out transposon to relocate it somewhere else

26

Types of Transposons

1. IS Element: composed of regular transposon structure

2. Complex transposon: composed of transposae with some other genes flanked with inverted repeats

3. Composite transposon: composed of 2 transposae with central region in middle

27

How do transposons contribute to genomic variation?

1. Transposase gene codes for the "cut & paste" transposae enzyme
2. Transposae cuts transposon out & pastes it somewhere else

28

Effect of ONE transposon vs TWO

If one transposon is inserted in:
Intergenic region, then likely no problems
Coding region, then could disrupt the gene & cause less proteins to be formed

If two transposons are inserted in:
Same direction - DNA loops around and causes both to pair up & delete some coding area (therefore loss of genetic info)

Opposite direction - DNA loops around and pair with each other BUT coding area is flipped (therefore less problematic, gene inversion, chromosome rearrangement)

29

Inversions

Piece of DNA is flipped

30

Amplifications

Region of gene is duplication therefore the amount of mRNA increases = increases proteins therefore disrupts homeostasis