Cell Replication

Question 1

What happens in mitosis interphase?

Answer 1

The cell grows and duplicates its DNA+organelles (centrioles)

Question 2

What happens in mitosis prophase?

Answer 2

• Chromatin condenses into chromosomes
• Mitotic spindles begin to develop
• Nuclear envelop breaks down

Question 3

What happens in mitosis metaphase?

Answer 3

• Spindles align at the poles
• Chromosomes align along the equator

Question 4

What happens in mitosis anaphase?

Answer 4

Kinetochore microtubules pull chromosmes towards poles

Question 5

What happens in mitosis telophase?

Answer 5

• Chromosomes decondense
• Nuclear envelope reforms
• Spindles dissapear

Question 6

What happens in how is meiosis M1 different from mitosis metaphase?

Answer 6

Chromosomes align in homologous pairs along the equator

Question 7

What are the differences between mitosis and meiosis?

Answer 7

• Mitosis is used in growth and repair of cells
• Mitosis also produces identical daughter cells only whereas meiosis produces gametes

Question 8

How do genetic stability and genetic variation contribute to the continuity of the species?

Answer 8

The inheritance of characteristics from ancestors to currently living organisms relies on the passing of consistently accurate information AND the occasional introduction of new genetic information. Accurate DNA replication brings about genetic stability, whereas mutations bring genetic variation.

Question 9

What does mitosis produce

Answer 9

2 diploid cells (2n)

Question 10

What does meiosis produce

Answer 10

4 haploid cells (n)

Question 11

What are recombinant chromatids?

Answer 11

When chromosomes cross over and genetic material is exchanged

Question 12

What is an allele?

Answer 12

An allele is one or two or more versions of DNA sequence (a single base or a segment of bases) at a given genomic location

Question 13

What is autosomal inheritance?

Answer 13

Autosomal inheritance is a way for a genetic trait or condition can be passed down from parent to child

Question 14

What is the Mendelian phenotypic ratios of heterozygous monohybrid crosses?

Answer 14

1:3

Question 15

What is the Mendelian phenotypic ratios of heterozygous dihybrid crosses?

Answer 15

9:3:3:1

Question 16

What are the 4 steps in DNA Replication?

Answer 16

1. Topoisomerase relaxes the double helix while helicase breaks hydrogen bonds between nucleic acids, unzipping the DNA strand. Single Strand Binding Protein (SSBP) stabilises the unzipped parent strands
2. The leading strand (3’-5’) is continuously synthesised by DNA polymerase
3. The lagging strand (5’-3’) is synthesised discontinuously. DNA primase synthesises a short RNA primer, which is extended by DNA polymerase to form Okazaki fragments
4. After the RNA primer is replaced by DNA, DNA ligase joins the Okazaki fragments to the growing strand

Question 17

What are the names and purposes of the four main enzymes involved in DNA replication?

Answer 17

• Helicase: unzips the helix and breaks hydrogen bonds
• Primase: synthesises short RNA sequences that are complementary to a single-stranded piece of DNA at the replication fork
• DNA polymerase: to replicate new DNA strands
• Ligase: to join Okazaki fragments and errors in the leading strand

Question 18

What are the main differences between DNA and mRNA

Answer 18

mRNA is a single-stranded, contains a ribose sugar instead of a deoxyribose sugar, has uracil instead of thymine