DNA and Protein Synthesis

Question 1

DNA

Answer 1

Deoxyribonucleic acid
Located in nucleus
Made of nucleotides

Question 2

Nucleotide

Answer 2

Composed of phosphate group, deoxyribose sugar and nitrogenous base

Question 3

Relationship between DNA, genes and chromosomes

Answer 3

Both chromosomes and genes are made of DNA
A gene is a section of DNA which codes for a particular characteristic
Chromosomes are tightly wound DNA which only appear in the nucleus at the start of cell division.

Question 4

DNA Replication (steps)

Answer 4

1. DNA is unzipped by an enzyme called helicase
2. The nucleotides of template are exposed
3. Primers (short segments of DNA) are needed to start the process. (Produced by enzyme= RNA primase) (DNA polymerase then add bases to template strand)
4. Ligase joins DNA strands together (DNA is re zipped) two identical DNA molecules are produced

Question 5

Neucleic Acids

Answer 5

DNA= deoxyribonucleic acid
RNA= ribonucleic acid

Question 6

Transcription

Answer 6

Occurs in nucleus
DNA unzips at the region to be copied
RNA polymerase attaches to DNA at promoter
Free nucleotides create mRNA
Uracil attaches to adenine
Transcription stops and RNA polymerase detaches from DNA releasing mRNA

Question 7

Introns

Answer 7

Are non coding segment of DNA in eukaryotic cells

Question 8

Exons

Answer 8

Coding segments of DNA that are involved in gene expression

Question 9

Translation

Answer 9

mrna moves into the cytoplasm
mRNA binds with a ribosome
Begins at a start codon
tRNA contains an anti codon
tRNA anticodon binds with mRNA codon releasing amino acid
Polypeptide chain continues to grow until stop codon is reached
Polypeptide forms a protein, travels to endoplasmic reticulum

Question 10

Eukaryote

Answer 10

Nucleoid region 
No membrane bound organelles 
Plasmids
Flagellum 
No histone

Question 11

Prokaryote

Answer 11

Membrane bound organelles
Nucleus
Histones

Question 12

Mitosis (interphase)

Answer 12

DNA is replicating, chromosomes are not visible

Question 13

Mitosis (prophase)

Answer 13

Chromosomes become visible, nucleolus and nuclear membrane disappear. Chromosomes appear as 2 chromatids joined by centromere. Crossing over occurs

Question 14

Mitosis (metaphase)

Answer 14

Chromatids line up along the equator, spindle fibres appear and attach to centromere.

Question 15

Mitosis (anaphase)

Answer 15

Centromere divides and the pair of chromatids seperate. Each pulled to opposite poles as spindle fibres shorten

Question 16

Mitosis (telophase)

Answer 16

Cytokensis occurs

2 identical daughters cells produced

Question 17

Meiosis (interphase)

Answer 17

Chromosomes replicate forming sister chromatids joined at centromere. Centrosome replicates forming two centrosomes

Question 18

Meiosis (prophase 1)

Answer 18

Chromosomes condense. Diploid number of chromosomes appear as long thin threads, they shorten and thicken. Crossing over occurs, nuclear membrane disappears. Spindle forms

Question 19

Meiosis (metaphase 1)

Answer 19

Pairs of chromatids line at the equator. Random assortment

Question 20

Meiosis (anaphase 1)

Answer 20

Chromosomes move towards the poles pulled by spindle fibres. Sister chromatids stay attached at centromere and move as one unit

Question 21

Meiosis (telophase 1)

Answer 21

Spindle disappears
Cytokinesis occurs
Two haploid cells form

Question 22

Meiosis (prophase 2)

Answer 22

Spindle apparatus forms, crossing over may cause sister chromatids to not be genetically identical.

Question 23

Meiosis (metaphase 2)

Answer 23

Sister chromatids line up at equator and attach to spindle fibres

Question 24

Meiosis (anaphase 2)

Answer 24

Centromeres seperate and sister chromatids are pulled apart and move to opposite poles.

Question 25

Meiosis (telophase 2)

Answer 25

Chromosomes reach poles and spindle disappears. Nuclei form, chromosomes begin condensing, nuclear membrane reappears, nucleolus becomes visible and cytokinesis occurs. Four daughter cells form

Question 26

Gene expression

Answer 26

Is the production of proteins

Question 27

Environmental factors

Answer 27

``` Climate Toxins Altitude Disease Soil pH Food availability Light availability Temperature ```

Question 28

Himalayan Rabbits

Answer 28

Pigment gene influenced by temperature Gene active when 15-25 Degrees celsius Fur turns black in colder temp 30+ degrees no pigmentation

Question 29

Point Mutation

Answer 29

Occurs when a single nitrogenous base is changed

Question 30

Insertion or Deletion

Answer 30

Addition or deletion of a single base | Can have dramatic affects as they cause a frameshift

Question 31

Substitution

Answer 31

When a single base is swapped with a different one

Question 32

Silent substitution

Answer 32

The single change results in the same amino acid being produced

Question 33

Non sense substitution

Answer 33

Results in a stop codon

Question 34

Mis sense substitution

Answer 34

The substitution results in a different amino acid

Question 35

Chromosomal mutation

Answer 35

Results from 2 or more breaks in the DNA helix and rearrangement of segments

Question 36

Deletions

Answer 36

Usually fatal Occurs when a strand is broken in two places and the segment is lost Results in a shorter chromosome

Question 37

Inversion

Answer 37

Cause of disorders | Chromosome breaks in 2 places and the segment rotates 180 degrees before rejoining

Question 38

Translocation

Answer 38

Often results in cancer | Occurs when a segment of one chromosome breaks off and attaches to another chromosome

Question 39

Duplications

Answer 39

``` Usually harmful (can result in beneficial traits) An extra copy of a section of a chromosome is made and then inserted into another region on the same chromosome or another chromosome. ```