inquiry question 2 mod 5

Question 1

cell division

Answer 1

process that cells undergo in order to form new cells
- mitosis
- meiosis

Question 2

what does DNA stand for

Answer 2

deoxyribonucleic acid

Question 3

chromosome

Answer 3

• thread like structures made of highly packed DNA around histone proteins
• allows DNA to be accurately copied during cell division
• located inside the nucleus of animal and plant cells
• can be duplicated 92 sister chromatids), unduplicated
• joined at centromere

Question 4

where are chromosomes found in plants and animals

Answer 4

plants: nucleus, mitochondria, chloroplasts
animals: nucleus, mitochondria

Question 5

homologous chromosomes

Answer 5

A pair of chromosomes that consists of one maternal and one paternal chromosome that are the same length and carry genes at the same locations

Question 6

cell cycle

Answer 6

series of events that take place in a cell as it grows and divides
- interphase –> mitosis –> completes division
- mainly interphase
- small part mitosis

Question 7

mitosis

Answer 7

process of nuclear division in which the replicated genetic material is separated and two new nuclei are formed
- parents cells create 2 identical daughter (2n) cells
eg. binary fission

Question 8

chromatids

Answer 8

one of two genetically identical halves of a replicated chromosome
sister: identical
non-sister: paternal and maternal

Question 9

phases of mitosis

Answer 9

(interphase before)
- prophase
- metaphase
-anaphase
- telophase
- cytokinesis (no part of mitosis)

Question 10

prophase (mitosis)

Answer 10

• chromatin condenses into chromosomes –> chromosomes become visible
• mitotic spindle fibres start to form from centrioles
• nuclear membrane dissolves to allow spindle fibres to attach to chromosomes

Question 11

interphase

Answer 11

DNA is replicated
- nucelar DNA remaind in semi condensed chromatin configuration
- amount of DNA doubles bu the amount of chromosomes remain the same

Question 12

metaphase (mitosis)

Answer 12

• chromosomes line up –independent assortment
• centrosomes are at opposite ends of cells –> poles
• spindle fibres attach to centromere of each pair of sister chromatids (makes sure that the chromatins go to different sides)

Question 13

anaphase (mitosis)

Answer 13

• sister chromatids pulled to opposite ends of the cell
• end: each pole has a full set of chromosomes

Question 14

telophase (mitosis)

Answer 14

• chromosomes begin to decondense (unravel)
• mitotic spindles break down
• nuclear envelope begins to form around the chromosomes

Question 15

cytokinesis

Answer 15

Division of the cytoplasm to form two new cells each with their own cell membrane
- Begins in either anaphase or telophase –> doesn’t finish until after telophase.
- Cytoplasm splits equally between the two cells.
- Chromosome unravels to become chromatin
- When cytoplasm divides so each daughter cell has its own cytoplasm

Question 16

meiosis

Answer 16

process of nuclear division required for the formation of new sex cells (gametes)
- single parent cell divided twice to produce 4 identical daughter cells that contain half the amount of genetic information
- 2n - 2n - nX4
- produces genetically unique gametes

Question 17

phases of meiosis

Answer 17

interphase
meiosis I
- prophase I
- metaphase I
- anaphase I
- telophase I
cytokinesis
(no interphase)
meiosis II
- prophase II
- metaphase II
- anaphase II
- telophase II
cytokinesis

Question 18

prophase I meiosis I

Answer 18

• chromosomes condense into x-shaped structures
• two sister chromatids in each chromosome
• pairs may cross over –> exchange DNA to mix maternal and paternal alleles –> increases genetic variability

Question 19

metaphase I meiosis I

Answer 19

• Homologous pairs of chromosomes line up on the equator randomly –> independent assortment –> increases genetic variability
• centrioles at opposite ends of the cell
• meiotic spindles attach to one chromosome from each pair on each side

Question 20

anaphase I meiosis I

Answer 20

• cells begin to elongate
• homologous pair of chromosomes are pulled apart by meiotic spindle
• sister chromatids stay attached at centromeres

Question 21

cytokinesis after meiosis I

Answer 21

• Single cell pinches in the middle→ two new daughter cells
• Each contain a full set of chromosomes within a nucleus

Question 21

telophase I meiosis I

Answer 21

• Chromosomes complete the move to the opposite poles of the cell
• each pole has a full sett of chromosomes
• chromosomes decondense
• nuclear envelope begins to form around each set of chromosomes

Question 22

meiosis II

Answer 22

• like mitosis
• no crossing oer
• begins without further replication –> interphase

Question 23

prophase II meiosis II

Answer 23

• two daughter cells (n)
• Nuclear envelope and nucleoli and membrane dissolve and disappear
• Spindle fibres form and spread across the two daughter cells
  (crossing over does not occur)

Question 24

metaphase II meiosis II

Answer 24

- Chromosomes line up along the equator of the cell → (metaplate) in a single file line different to metaphase I - law of independent assortment - meiotic spindles attach to each of the sister chromatids

Question 25

anaphase II meiosis II

Answer 25

- Sister chromatids are pulled apart to opposite poles due to the meiotic spindle - one chromatid = one chromosome

Question 26

telophase II meiosis II

Answer 26

- chromosomes complete their move to opposite poles of the cell - chromosomes decondense - nuclear envelope begins to reform around them

Question 27

cytokinesis (after meiosis II )

Answer 27

- cells physically divide into four daughter cells - haploid (23 chromosomes)

Question 28

gene

Answer 28

a distinct sequence of nucleotides on a chromosome which code for some characteristic which is transferred from parent to offspring

Question 29

allele

Answer 29

each of two or more alternative forms of a gene that are found at the same place on a chromosome - dominant: when the allele of the gene effectively overruled the other (recessive) allele

Question 30

genetic continuity

Answer 30

ability to pass on genetic information from one generation to the next depends on - large numbers - stable environment in changing environment variation helps continuity

Question 31

why is genetic continuity important

Answer 31

allows for the passage of advantageous traits to ensure species survival

Question 32

how does sexual reproduction ensure genetic variation and continuity

Answer 32

1. crossing over 2. law of independent assortment 3. law of random segregation 4. random fertilisation

Question 33

crossing over

Answer 33

- Exchange of genetic material between two homologous chromosomes’ non-sister chromatids - Prophase I or metaphase I - Leads to new allelic combination in daughter cells

Question 34

law of independent assortment

Answer 34

- metaphase --> homologous pairs align independently - Traits are inherited independently - the allele a gamete receives for one gene does not influence the allele received for another gene

Question 35

law of random segregation

Answer 35

chromosomes are distributed randomly among the different gametes depending on which way in which chromosome pairs line up during meiosis - results in unique set of chromosomes - anaphase I - Alleles separate/segregate → each gamete is equally likely to receive either on of the two alleles present in the diploid individual

Question 36

random fertilisation

Answer 36

Random union of gametes during fertilisation → introduces variability - any sperm can combine with any egg