Topic 1 - Introduction

Question 1

Cell Doctrine (1838) - 3 Key Players

Answer 1

• Schwann
• Schleiden
• Virchow

Question 2

Cell Doctrine - 3 main points

Answer 2

1) Cells are the smallest living unit
2) Cells are distinct units with specific tasks
3) A cell is only derived from another cell (Virchow) - put to rest spontaneous generation
* * Viruses are the only exception

Question 3

Commonalities between all cells?

Answer 3

• store hereditary information
• replicate hereditary information
• transcribe part of the genetic information into RNA
• translate RNA into proteins
• proteins are used as catalysts for function
• biochemical factories use the same molecular building blocks
• enclosed in plasma membranes

Question 4

What are the 4 basic features of all cells?

Answer 4

• membranes
• DNA
• ribosomes
• cytosol

Question 5

What is significant about the Mycoplasma?

Answer 5

• only has 500 genes (the smallest amount for life)

Question 6

4 Metabolic Pathways & general sizes of cells

Answer 6

• photoautotroph
• photoheterotroph
• chemoautotroph
• chemoheterotroph
• 1-10 micrometers

Question 7

2 Methods of identifying bacteria?

Answer 7

1) Culture dishes - however we have only grown and named 5000 species of bacteria (>90% not cultivated yet)
2) DNA sequencing

Question 8

2 unique features to Animal Cells

Answer 8

• centrosomes

- lysosomes

Question 9

4 unique features of Plant Cells

Answer 9

• chloroplasts
• central vacuoles
• plasmodesmata
• cell walls

Question 10

Feature shared by plant and animal cells

Answer 10

mitochondria

Question 11

What are the advantages of compartamentalization

Answer 11

1) Each area has a distinct pH - allows enzyme functionality to depend in specific pH’s - as a fail safe
2) Gradients across membranes do work
3) Arrangements of protein complexes in membranes allow reactions to occur faster

Question 12

What do bacteria and mitochondria have in common?

Answer 12

• the both have their own genome, membrane, own ribosomes and machinery

Question 13

What organelle was taken up first - chloroplast or mitochondria

Answer 13

• only plant cells have chloroplasts while all eukaryotes have mitochondria

Question 14

Number of Prokaryotes genes

Answer 14

roughly 4000 genes , mycoplasma exception

Question 15

Number of Eukaryotic genes

Answer 15

21000-30000 genes

Question 16

Comparisons between prokayotes and eukaryotes - genes?

Answer 16

• Eukaryotes have 3-30X more genes than prokaryotes

- Eukaryotes have 1000X more NON-CODING DNA

Question 17

Why do eukaryotes have gene splicing or post translational modifications?

Answer 17

Eukaryotes have hybrid genomes - the human genome has about 98% non-coding for proteins compared to prokaryotes with 11% of its DNA being non-coding for proteins

Question 18

Is there a correlation between genome size and level of organization?

Answer 18

1) NO - compare a human genome to amoeba*

2) YES - correlation with function requirement - meaning tissues with higher level of organization

Question 19

Is there a correlation between genome size and level of organization? (2) - house renter vs house buyer

Answer 19

1) Prokaryotes are house renters - require mobility thus only produce essential structures, smaller genomes are used to compete for nutrient since there is a pressure to replicate
2) Eukaryotes are house buyers - takes 12hours to replicate its genome, has sites for storage, and contains coding & non-coding regions in its genome

Question 20

Once you double genome size…

Answer 20

… you do NOT double in size

Question 21

Does the number of chromosomes correlate with the level of organization?

Answer 21

NO CORRELATION - in the example, each species have the same number of genes, but one has a significantly larger genome size

Question 22

Genes and NON-coding regions on Chromosomes

Answer 22

• repeated sequences consist of 50% of a chromosome
• 40% of these are transposons
• segmental duplication of bases

Question 23

Define pseudogenes

Answer 23

• segments related to genes however they have lost their functionality to a complete gene (in terms of cellular gene expression or protein coding ability)

Question 24

Are genomes of Humans Identical?

Answer 24

NO

a) SNP (single nucleotide polymorphism)
- variation in single nucleotides occurring in a specific position in a genome - each variation is present to some degree within a population
b) duplication/deletion - of large areas of a genome

Question 25

How do we generate Junk DNA?

Answer 25

• accumulation of mistakes during DNA replication which never got fixed 100%

Question 26

4 ways to accummulate Junk DNA

Answer 26

1) Intragenic Mutation - insertion/deletions
2) Gene Duplication - via transposons
3) DNA segment suffling
4) Horizontal Gene Transfer - integration of genes into other organisms (Vertical gene transfer - normal transfer of genes from parent to offspring)

Question 27

Explain an Ortholog

Answer 27

when an ancestral organism with gene G undergoes SPECIATION giving: Gene Ga and Gene Gb - these two genes are called ortholog’s since they descended from a common ancestor & and encode for a protein with the same function

Question 28

Explain a Paralog

Answer 28

when an ancestral organism with Gene G undergoes GENE DUPLICATION and DIVERGENCE allowing later ancestral organisms to have Gene G1 and Gene G2 - these homologous genes involved in gene duplication encode for a protein with sSIMILAR but NOT IDENTICAL function

Question 29

Eukaryotes have regulatory DNA which allows them to (2)

Answer 29

• selectively use the genetic information

- use environmental signals to activate selective sets of genes

Question 30

Regulatory DNA through signalling cascades turn genes on and off having what 3 effects

Answer 30

• metabolic enzymes
• transcription regulatory proteins
• cytoskeletal proteins