Chapter 2.1 The Continuity of Life ✓

Question 1

What are the 3 principles of cell theory?

Answer 1

-Cells are the basic unit of life
-All living things are made up of cells
-Cells arise from pre-existing cells

Question 2

Define cell division

Answer 2

The splitting of a cell into two new functioning cells

Question 3

Why do cells require cell division?

Answer 3

Its required for growth, development, repair and reproduction

Question 4

Define heredity

Answer 4

Its the study of the processes that are involved in transmitting genetic material to the next generation.

Question 5

Define mitosis

Answer 5

A type of nuclear division in somatic cells that maintains the parental diploid number of chromosomes in the daughter cells

Question 6

Define meiosis

Answer 6

A type of cellular division in sexually reproducing organisms that involves two rounds of cell division, but only one round of DNA replication

Question 7

Define fertilisation

Answer 7

The fusion of haploid male and female gametes during sexual reproduction to produce a diploid zygote.

Question 8

Define DNA

Answer 8

Is the genetic material that is passed on to offspring for the continuity of life

Question 9

Define eukaryotic cells

Answer 9

They are complex cells containing many membrane bound organelles, including a nucleus

Question 10

Where is DNA found in a eukaryotic cell?

Answer 10

-In the nucleus bound to histone proteins
-DNA is also found in the chloroplasts and mitochondria but its isn’t bound to proteins

Question 11

Define chromatin

Answer 11

An organised, loosely coiled complex of DNA and its proteins that is found in eukaryotic non-dividing cells.

Question 12

Define chromosome

Answer 12

An structure composed of DNA and protein that contains linear arrays of genes carrying genetic information
-Prokaryotes have one circular chromosome whereas eukaryotes have a number of linear chromosomes

Question 13

Define centromere

Answer 13

-The waist constriction in a chromosome where the spindle fibres attach
-It enables the movement of chromosomes during cell division

Question 14

Define karyotype

Answer 14

A display of the number and appearance of the chromosomes of an organism or cell as observed at metaphase

Question 15

In a somatic cells of a human, how many chromosomes are in the nucleus?

Answer 15

46 chromosomes OR 23 pairs

Question 16

Define gene

Answer 16

A segment of DNA that codes for a polypeptide (short chain of amino acids)

Question 17

Define paternal and maternal chromosome

Answer 17

-Paternal: The chromosome in a pair of chromosomes that came from the father
-Maternal: The chromosome in a pair of chromosomes that came from the mother

Question 18

Define autosomes

Answer 18

A chromosome that is not sex chromosome

Question 19

Define heterosome

Answer 19

One of the non-identical chromosomes that pairs up at meiosis (e.g. the X and Y chromosomes in male humans)

Question 20

Define sex chromosome

Answer 20

A chromosome that determines the sex of an organism and affects sexual traits

Question 21

Define germline cells

Answer 21

A specialised sex cell that gives rise to gamtes

Question 22

Define differentiation

Answer 22

The process during development whereby newly formed cells become more specialised as they mature

Question 23

Define diploid and haploid number

Answer 23

-Diploid: (2n) Contains 46 chromosomes
-Haploid: (n) Contains 23 chromosomes

Question 24

Define locus (plural loci)

Answer 24

It is the specific location of a gene on a chromosome

Question 25

Define allele

Answer 25

Versions of the same gene with slight differences

Question 26

Define prokaryote

Answer 26

A single-celled organism that lacks membrane organelles such a nucleus

Question 27

Define nucleoid

Answer 27

The region within a prokaryotic cell that contains the genetic material

Question 28

Define plasmids

Answer 28

A small circular piece of DNA found in bacteria.

Question 29

In prokaryotes, where is DNA found?

Answer 29

DNA is found in the cytosol as unbound circular DNA

Question 30

Define asexual reproduction

Answer 30

The process by which a single parent produces offspring and that does not involve fusion of gametes

Question 31

Define sexual reproduction

Answer 31

A form of reproduction in which offspring are produced from two parents by the fusion of male and female gametes

Question 32

Name 5 differences between prokaryotes and eukaryotes

Answer 32

Diameter -Prokaryotes: 1-5 micrometers -Eukaryotes: 10-100 micrometers Location of DNA -Prokaryotes: In cytosol (in nucleoid) -Eukaryotes: In nucleus, mitochondria and chloroplasts Membrane-bound organelles -Prokaryotes: No -Eukaryotes: yes e.g. nucleus Ribosomes -Prokaryotes: Float freely in the cytosol -Eukaryotes: Float freely in the cytosol OR be attached to endoplasmic reticulum Chromosomes -Prokaryotes: A single circular DNA strand (typically without histones) -Eukaryotes: DNA wraps around histones to from nucleosomes, creating chromatin. Chromatin condenses into chromosomes for mitosis or meiosis.

Question 33

Describe the process of constructing a karyotype

Answer 33

-A sample of dividing cells is collected and treated to stop division at metaphase. -The cells are stained and photographed under a microscope. -Chromosomes are then arranged into homologous paris based on size ordered from largest to smallest with sex chromosomes last. -This karyotypes is used to analyse chromosome number and structure.

Question 34

Label the levels of organisation of a human chromosome (image on preview)

Answer 34

a) Tightly coiled and condensed human chromosome b) Nucleosome c) Chromatin d) Chromosome