Chapter 2

Question 0

Explain how cell division is responsible for growth

Answer 0

Once the cell grows beyond the a certain size it cannot function properly so it divides creating two smaller cells that will perform the same functions

Question 1

Give three reasons why cells divide

Answer 1

To grow, repair, and reproduce

Question 2

Why do cells reproduce faster than other types of cells?

Answer 2

Skin cells can reproduce faster because they are constantly dying off

Question 3

Give a location where cells might reproduce faster than others

Answer 3

Blood
Heart
Cheek bones
Brain

Question 4

A) broken leg
B) lizard shedding skin
C) bacteria
D) puppy

Answer 4

Repair
Grow
Reproduce
Grow

Question 5

What are the sides of the ladder made of

Answer 5

Phosphate and sugar

Question 6

What Re the rungs made of

Answer 6

Nitrogenous bases

Question 7

Name of each of the molecules that make up the rungs

Answer 7

Adenine (A) 
Thymine (T) 
Cytosine (C)
Guanine (G) 
A-T always go together 
C-G always go together 
These are called base pairs

Question 8

Describe how the Dna molecule replicates

Answer 8

Each Dna molecule splits in many places between he pairs of bases like a broken zipper. New bases join up with bases in each of the opened sides of he ladder to form 2 identical Dna molecules. Since the base pairs always line up the Dna molecule is identical. So it has a old strand and a new strand of Dna

Question 9

What part of the Dna molecules determines the genetic code of an organism

Answer 9

The bases of Dna

Bases combine to form three letter words each of these is a code for one of 20 different amino acids .

Question 10

What is a human genome

Answer 10

All of an organisms genes is called a genome. It contains the 23 pairs of chromosome int the nucleus of almost every cell in the body

Question 11

Where are proteins made

What are the building blocks of proteins

Answer 11

In the ribosomes

Amino acids

Question 12

How is the genetic code transferred from the nucleus to the cytoplasm

Answer 12

Dna segement that make a gene is used to make another molecule called RNA. A gene segment of Dna separates and an rna molecule is constructed from one half of the DNS the rna molecule than carries the code from the gene out of the nucleus to a ribosome in the cytoplasm the ribosome reads the instructions on the rna and assembles the appropriate amino acids in the correct order to make the protein

Dna unzips -> RNA COPIES DNA SEGMENT -> ribosome assembles amino acids into a protein

Question 13

Genes

Answer 13

Codes for a specific protein
Our genes determine our traits we have
Genes also control the proteins made in our cells

Question 14

Nucleus

Answer 14

The control centre of the cell. Directs and controls all of the cells activities include the ability of the cell to grow, develop, and replicate
In the nucleus the instructions for how to perform all cell activities are carried in molecules of DNA

Question 15

DNA

Answer 15

DNA store the instructions for how to form cells for the chemicals and structures that cells must make and for everything that the cell does
It also stores the genetic material information passed down from generation to generation when organisms reproduce

Question 16

DNA related to chromosomes and genes

Answer 16

Stands of DNA are packed tightly into structures called chromosomes. each type of organism has a specific number of chromosomes. Humans have 46 chromosomes arranged into 23 pairs

Genes are found at a specific place on a chromosome. genes are small segments of DNA that carry the instructions for making proteins. Proteins are molecules that all the cells of the body need in order to work properly. 100,000 proteins in the human body

Question 17

Proteins made where?

Answer 17

They are made in the cell by ribosomes. ribosomes are made by a large structure in the nucleus called the nucleolus

Question 18

Centriole

Answer 18

Organelle made of special micro tubules

Question 19

Nucleotide

Answer 19

Molecule made of sugar molecule, phosphate molecule, and a nitrogenous base

Question 20

Trait

Answer 20

One version of a characteristic

Question 21

Sister chromatids

Answer 21

A chromosome and its copy

Chromosomes make copies of themselves in interphase

Question 22

Parent cell

Daughter cell

Answer 22

A cell before it divides

One of the two identical cells produced when a parent cell divide

Question 23

The cell cycle

Answer 23

90% in interphase
10% in cell division
3 stages
Interphase: this stage make up most of the cells life. Cells grow and carry out normal life functions in cells that will divide the nucleus makes a copy of its DNA in a process called replication
Mitosis: the nucleus divides into two equal and identical parts. each part has a copy of the DNA
Cytokinesis: the two equal and identical parts of the cell separate. the result is two identical cells each with a nucleus and DNA

Question 24

Phases of mitosis

Answer 24

4 phases of mitosis Prophase: the duplicated chromosomes form into an X shape and the nucleolus disappears called sister chromatids and the join in the centre Centrioles form spindle fibres or microtubules which are tiny tube like structures made of protein Metaphase: the sister chromatids attach to the spindle fibres and line up across the middle of th cell Anaphase: sister chromatids are pulled apart to opposite parts of the cell They are now called chromosomes again Telophase: a nucleolus forms around the chromosomes at the opposite ends of the dividing cell Nuclear membrane reforms

Question 25

Cytokinesis

Answer 25

Division of the organelles | Cell pin she's down the middle to form 2 daughter cells

Question 26

Cell division

Answer 26

New cells arise from pre existing cells 3 main functions growth repair and reproduction Growth: cells have limits to their size Too big can't function so they divide into two smaller cells Specialized cells form tissues and organs Repair: damaged cells are repaired by being replaced You have 100,000,000,000,000 cells About every 7 years these cells are all replaced except for brain and heart muscle cells Reproduction: single celled organisms reproduce by cell division Ex. Paramecium, ameba, euglena Multicellular organisms humans reproduce through sexual reproduction 2 cells Combine to form a zygote

Question 27

Asexual reproduction

Answer 27

Only one organism needed to reproduce All the offspring are genetically identical to each other and to the parent A single organism can produce large number s of offspring 1. Binary Fission Only occurs in single celled organisms Parent undergoes mitosis to produce 2 identical daughter cells Examples ameba paramecium bacteria 2. Budding Offspring begins as a small growth on the parent Offspring breaks off and becomes independent Hydra 3. Vegetative reproduction Occurs in plants Plants send out runners or shoots which grow into new plants Strawberries spider plants 4. Fragmentation A part breaks off and grows into a new organism Regeneration occurs in both the parent and the piece that breaks off Starfish planaria 5. Spore formation Spore are like seeds but they don't need pollination or fertilization Spore grow into a new organism in the same way a seed grows into a plant Ferns or puff balls

Question 28

During the process of cloning scientists ...

Answer 28

Remove the nucleus from an egg cell

Question 29

Advantage of asexual reproduction

Answer 29

Large numbers of offspring reproduce quickly

Question 30

Disadvantage of asexual reproduction ...q

Answer 30

Extreme temperature can wipe out entire colonies

Question 31

Mutation

Answer 31

Is a change in the genetic material DNA of a gene. Changes in the DNA may cause proteins to be made incorrectly or with incorrect shape

Question 32

Mutagen

Answer 32

Factors in the environment that causes a mutation | X Rays UV Rays (tanning) cigarette smoke and posing us chemicals such a s pesticides

Question 33

Types of mutations

Answer 33

Negative mutations: can be harmful to the organism. For example some people are born with a mutated gene that makes their red blood cells have a curved shape instead of the normal disc shape. The curved shape prevents the cells from carrying oxygen well and blocks the blood flow to blood vessels Positive: some can be helpful to the organism. Some plants carry a mutated gene that protects them from certain diseases. Some people have a mutated gene that produces a special protein that prevents them from H.I.V infecting them. This type benefits an individual Neutral: these have no effect on the organism Most mutations are neutral Spirit bear has a mutated gene that causes their fur to be white instead of black. This mutation does not in any way affect their lives.

Question 34

Gene therapy

Answer 34

Some mutations as an be treated with drugs and surgery. New techniques for treating gene mutations is called gene therapy. Researchers must replace the mutated gene with a healthy copy. The good gene must first attach to the chromosomes. Then the gene must make the appropriate type and amount of protein. Still experimental

Question 35

Cloning

Answer 35

Type of asexual reproduction A single cel is used to grow a clone How 1. Nucleus of a cell from the donor is combined with an empty egg -> DNA removed 2. Cell undergoes mitosis, grows into an embryo ( in a lab) 3. Embryo is implanted into a mother which carries out the developing clone 4. Mother gives birth clone is identical to the donor NOT the mother

Question 36

Pros and cons of cloning

Answer 36

Pros Clone livestock cows and chickens for food Clone animals to grow humans organs for transplant Cons Mutations and new diseases Ethical issues

Question 37

Stem cells

Answer 37

Stem cells have the ability to divide and form many different types of cells Embryonic stem cells can become almost any human cells Researchers use discarded embryos from fertility clinics This requires the destruction of the embryo ``` Benefits Grow new organs for transplant Repair and replace damaged tissue ex. Spinal injuries Replaced diseased cells Future discoveries for more research ``` Cons Ethical issues Mutations, new disease arise from research

Question 38

Cancer

Answer 38

Mutagens can cause changes in the cell cycle so that the cells keep dividing continuously. The cells pile up on top of each other forming a lump or a Tumour. The uncontrolled cell division sometimes results in cancers. Mitosis when it is out of control Cells divide rapidly over and over -> results in lumps of tumours A mutation in the genes that control the mitosis cause it to go out of control Cancerous cells have these characteristics 1. Cancer cells have an enlarged nucleus 2. Use more nutrients than normal 2 types of tumours form by cells dividing 1. Benign Cells grow and divide but stay in one place Don't usually interfere with the other tissues Ex warts 2. Malignant Cells invade surrounding tissues and prevent normal cell functions This spreading is called metastasis Causes Carcinogens anything that causes cancer Treatments 1. Surgery remove the tumours before. They metastasis spread 2. Radiation kill the cells by disrupting cell division (very targeted) 4. Chemo therapy using drugs or chemicals to stop cells from dividing Chemical therapy Radiation and chemo also kill healthy cells too They kill the fast growing or dividing cells so that also includes hair and skin cells so that means that sometimes people will start losing their hair and get burns on their skin