Chapter 7 - Heredity

Question 1

What is chromatin?

Answer 1

Substance that makes up chromosones (DNA + Protein (Histones))

Question 2

What are Histones?

Answer 2

Small proteins which DNA wraps around to create chromatin.

Question 3

What are germline cells?

Answer 3

Somatic cells whose specify role is to undergo meiosis and create gametes.

Question 4

Autosomal chromosones

Answer 4

Non- sex determining chromosome

Question 5

What are somatic cells?

Answer 5

Diploid (2N), non sex cells with a set of paired chromosones

Question 6

Base pairings?

Answer 6

Guanine & Cytosine

Adenine & Thymine

Question 7

What direction in terms of 5’ and 3’ does DNA travel and where are the 5’ and 3’ located in terms of chemical structure.

Answer 7

DNA travels 5’—> 3’
5’ : pentose sugar & Phosphate (same monomer)
3’ : pentose sugar & Phosphate (different monomer)

Question 8

Bond between DNA monomers?

Answer 8

Phosphodiesther bond

Question 9

Differences between DNA and RNA

Answer 9

DNA : double stranded, one less oxygen in ribose, carries all genetic info
RNA: single stranded, thymine replaced by uracil, carries only info required for protein synthesis

Question 10

4 steps from DNA —> Protein

Answer 10

Unwinding
Transcription (pairing)
Splicing
Translation

Question 11

Steps of cell cycle in order:

Answer 11

Interphase
Prophase 
Metaphase
Anaphase
Telophase
Cytokinesis
Interphase

Question 12

How does binary fusion occur?

Answer 12

Single DNA chromosome is replicated, following which the identical chromosomes are separated allowing a cell wall to form before cell splits into two identical cells.

Question 13

Prophase:

Answer 13

Nuclear membrane disintegrates
chromatin condenses revealing chromosomes
centrioles move to poles and spindles form

Question 14

Metaphase:

Answer 14

Chromosomes attach to spindle fibres and align themselves at equator.

Question 15

Anaphase:

Answer 15

Chromatids are pulled apart towards the poles.

Question 16

telophase: (Animal & Plant)

Answer 16

Nuclear membrane forms creating two nuclei.
chromosomes begin to lengthen and disappear
Animal: Cell membranes cleave
Plant: Cell plates form

Question 17

cytokinesis: (animal & plant)

Answer 17

Animal: cells are cleaved. Two cells remain
Plant: Cell plates extend to meet cell wall. Two cells remain

Question 18

Meiosis 1:

Answer 18

Chromosomes appear
Nuclear membrane disintegrates
Crossing over can occur
Centrioles move to poles

Question 19

Metaphase 1;

Answer 19

Homologous chromosomes (bivalents) line up independently along equator in pairs.
Crossing over occurs

Question 20

Anaphase 1:

Answer 20

Homologous chromosomes seperate apart (Disjunction)

Question 21

Telophase 1:

Answer 21

Cell division

Now remain 2, 1n cells

Question 22

DNA replication process.

Answer 22

Helicase : splits & unwinds DNA
DNA polymerase 3, synthesises DNA on Leading strand.
On complementary strand:
RNA Polymerase, makes short RNA primer
DNA polymerase 3 synthesises Okazaki fragments
DNA polymerase 2 digests RNA primer and replace with DNA
DNA lipase join Okazaki fragments into continuous strand

Question 23

Meiosis division 1 summary:

Answer 23

Chromosomes appear in prophase and align in homologous pairs at equator in metaphase. Crossing over occurs before homologous chromosomes separate in anaphase and cleave into two cells in telophase. Both remaining cells are haploid.

Question 24

Meiosis division 2 summary:

Answer 24

Spindles form at right angles to before meaning chromosomes align independently along equator 90° to before during metaphase 2. Chromatids separate in anaphase 2 and cleave into 4 seperate haploid gametes during telophase 2 and cytokinesis.

Question 25

Why is DNA replication semi-conservative.

Answer 25

Both strands of original DNA helix act as template for DNA replication. The two new DNA Helixes both have one strand from the original helix and new one and are hence semi-conservative.

Question 26

Triplet vs Codon Vs anticodon

Answer 26

Three DNA bases coding for one amino acid = Triplet. Three mRNA bases coding for one amino acid = codon Three tRNA bases coding for one amino acid = anti-codon

Question 27

How genetic diversity occurs

Answer 27

- Chromosomes align independently in metaphase 1 (& 2?) | - Crossing over metaphase 1 (sometimes P1)

Question 28

Mendel's Law of Independant Assortment

Answer 28

During Meiosis chromosomes and subsequent alleles align and separate randomly resulting in a random assortment of alleles in gamete production.

Question 29

Mendel's law of segregation;

Answer 29

Each pair of alleles will separate independently during gamete formation. When sperm and egg fertilise each contributes an allele to the offspring which is 2n.

Question 30

Allele Vs Gene

Answer 30

- Gene a sequence of DNA which codes for the production of a protein - Allele is a varient form of a gene located at a gene loci and codes for a particular phenotype.

Question 31

codominance

Answer 31

Both alleles are fully expressed in phenotype | Black + White = Black & white striped

Question 32

Why do various heights occur?

Answer 32

- Height is polygenetic and is influenced by multiple genes. - Height is also influenced by a range of environmental factors. - This results in continuous variation rather than discontinuous variation.

Question 33

Clues for sex linked recessive

Answer 33

- In general males effected more | - Female usually carriers, males cannot carry

Question 34

Clues for autosomal recessive Vs autosomal dominant

Answer 34

Recessive: Possible for allele to be carried Dominant: allele cannot be carried

Question 35

Clues for sex linked dominant

Answer 35

effect males pass on trait to all females

Question 36

``` AB ab ---- & ----- ab ab Gametes of each paretn Parental & recombinant genes ```

Answer 36

Gamete P1: AB & ab Gamete P2: ab Parental: ab/ab or AB/ab Recombinant: Ab/ab or Ba/ab

Question 37

S Phase of mitosis

Answer 37

DNA replication (synthesis)

Question 38

G2 Phase of mitosis

Answer 38

Cell prepares for cell division | Chromosomes begin to condense

Question 39

G1 Phase of mitosis

Answer 39

Cell growth | before DNA replication

Question 40

Phases of Cell cycle

Answer 40

G1 ---> S --> G2 ---> Mitosis --> Mitosis