Chapter 2 Flashcards
Explain how cell division is responsible for growth
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
Give three reasons why cells divide
To grow, repair, and reproduce
Why do cells reproduce faster than other types of cells?
Skin cells can reproduce faster because they are constantly dying off
Give a location where cells might reproduce faster than others
Blood
Heart
Cheek bones
Brain
A) broken leg
B) lizard shedding skin
C) bacteria
D) puppy
Repair
Grow
Reproduce
Grow
What are the sides of the ladder made of
Phosphate and sugar
What Re the rungs made of
Nitrogenous bases
Name of each of the molecules that make up the rungs
Adenine (A) Thymine (T) Cytosine (C) Guanine (G) A-T always go together C-G always go together These are called base pairs
Describe how the Dna molecule replicates
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
What part of the Dna molecules determines the genetic code of an organism
The bases of Dna
Bases combine to form three letter words each of these is a code for one of 20 different amino acids .
What is a human genome
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
Where are proteins made
What are the building blocks of proteins
In the ribosomes
Amino acids
How is the genetic code transferred from the nucleus to the cytoplasm
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
Genes
Codes for a specific protein
Our genes determine our traits we have
Genes also control the proteins made in our cells
Nucleus
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
DNA
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
DNA related to chromosomes and genes
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
Proteins made where?
They are made in the cell by ribosomes. ribosomes are made by a large structure in the nucleus called the nucleolus
Centriole
Organelle made of special micro tubules
Nucleotide
Molecule made of sugar molecule, phosphate molecule, and a nitrogenous base
Trait
One version of a characteristic
Sister chromatids
A chromosome and its copy
Chromosomes make copies of themselves in interphase
Parent cell
Daughter cell
A cell before it divides
One of the two identical cells produced when a parent cell divide
The cell cycle
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
Phases of mitosis
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
Cytokinesis
Division of the organelles
Cell pin she’s down the middle to form 2 daughter cells
Cell division
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
Asexual reproduction
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
- Binary Fission
Only occurs in single celled organisms
Parent undergoes mitosis to produce 2 identical daughter cells
Examples ameba paramecium bacteria - Budding
Offspring begins as a small growth on the parent
Offspring breaks off and becomes independent
Hydra - Vegetative reproduction
Occurs in plants
Plants send out runners or shoots which grow into new plants
Strawberries spider plants - 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 - 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
During the process of cloning scientists …
Remove the nucleus from an egg cell
Advantage of asexual reproduction
Large numbers of offspring reproduce quickly
Disadvantage of asexual reproduction …q
Extreme temperature can wipe out entire colonies
Mutation
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
Mutagen
Factors in the environment that causes a mutation
X Rays UV Rays (tanning) cigarette smoke and posing us chemicals such a s pesticides
Types of mutations
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.
Gene therapy
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
Cloning
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
Pros and cons of cloning
Pros
Clone livestock cows and chickens for food
Clone animals to grow humans organs for transplant
Cons
Mutations and new diseases
Ethical issues
Stem cells
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
Cancer
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
- Benign
Cells grow and divide but stay in one place
Don’t usually interfere with the other tissues
Ex warts - 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
