Bio yr 11

What is a genome?

The entire genetic information of a cell or organism

What is a gene?

A short section of DNA that codes for a specific polypeptide

What is a chromosome?

A long section of DNA with multiple genes wrapped around it

What is DNA?

A polymer of nucleotides stored in the nucleus of eukaryotic cells.

What is mRNA?

The messenger RNA which carries transcribed genetic information to the ribosome

It is made in the nucleus and is single stranded

What is tRNA?

Associated with the codons of mRNA‘s to build proteins at the ribosome

Each tRNA carries a specific amino acid

They transfer RNA

What is the site of protein synthesis?

The ribosomes

A protein is a

Polypeptide and is a chain of amino acids.

What is DNA made up of?

A base, a sugar and a phosphate

DNA is a …

Polymer

What do the strands in DNA form?

They form a double helix

What base is complementary to adenine?

Thymine

What base is complementary to guanine?

Cytosine

What are nucleotides?

The individual monomer subunits of DNA

What controls which types of amino acids will be joined together to make a protein

The order of the bases → triplet codes

What are the 5 key stages of protein synthesis?

1. A small section of the DNA molecule containing the gene unzips

2. The DNA is transcribed and mRNA is formed

3. The mRNA molecule moves to a ribosome in the cytoplasm

4. The tRNA molecules carry amino acids which join to form a protein

5. The nucleotide sequence has been translated

Describe the process of transcription

A small section of DNA containing the gene unzips. Then mRNA is made using the DNA as a template to copy from. The complementary bases are paired but there is no T so uracil (u) is paired with A.When the strand of mRNA detaches itself from the DNA and the DNA zips itself back up.

Describe the process of translation

The mRNA molecule moves to a ribosome in the cyptoplasm. A molecule of tRNA is used to carry amino acids to the mRNA strand. Amino acids that match triplet codes on the mRNA are joined together in the correct order. This forms a protein.

What is mitosis?

The process that replaces worn out/ damaged cells and produces 2 genetically identical daughter cells

What does it mean for 2 cells to be genetically identical?

When each cell has the same genetic information because they are copies of each others. They have the same genome.

Give an example of mitosis

Human embryonic and foetal development

What happens to cells as the embryo continues to grow?

The cells divide by mitosis and differentiate to form different tissues and organs

What is meant by “ parents” cells?

The cells that are used for cell division

What is meant by “ daughter “ cells

The new cells produced during cell division.

What happens in stage 1 of the cell cycle?

The cell replicates it's DNA ready to form 2 copies of each chromosome

They also increase their sub-cellular structures

What happens in stage 2 of the cell cycle?

The nucleus divides

Chromosomes are pulled to the opposite ends of the cell by a network of protein fibres and separate

What happens in stage 3 of the cell cell?

The cyptoplasm and cell membrane also divide to form 2 daughter cells

What is an alternative name for stage 1 of the cell cycle?

Interphase

What is an alternative name for stage 2 of the cell cycle?

Mitosis

What is an alternative name for stage 3 of the cell cycle?

Cytokinesis

What is auxin?

If causes cell elongation, phototropism, gravitropism and is a growth regulator

They promote cell growth

Where is auxin produced?

It is produced at the tip of the shoot

What is phototropism related to ?

Light

What happens when light falls evenly on the shoot?

The level of auxin are balanced out so the plant will grow straight up

What happens in uneven light conditions?

The auxin moves to the unlit side so it grows more and this causes the plant to bend towards the light → cell elongation

What is + phototropism?

Growth towards light

What is - phototropism?

Growth away from the light

Does auxin have the same or different effect on roots and shoots?

Different

Which side of the root do high levels of auxin accumulate on?

The lower side of the root

The side of the root with the _ auxin grows more making the root bend and grow towards gravity

The side of the root with the least auxin grows more making the root bend and grow towards gravity

In shoots, which side does the auxin gather on

The lower side

The shoot grows on the side with the … auxin

Most

Shoots bend and grow … from gravity

Away

Do roots do + or - gravitropism?

Positive

Do shoots do + or - gravitropism?

Negative

Growth responses are called … and they are controlled by …

Growth responses are called tropisms and they are controlled by hormones

Shoots grow towards … and away from …

Shoots grow towards light and away from gravity

Shoots grow upwards so that they can…

Obtain light for photosynthesis

Roots grow away from … and towards •… and …

Roots grow away from light and towards moisture and gravity

Roots grow downwards into the soil so that they can obtain …

water for the plant

What are 3 uses of auxin by humans?

1. Propogating plants

2. Weed killers

3. Rooting powders

What does it mean to propagate a plant?

To make new plants from existing ones by cutting a small piece of a stem and placing it in a specially prepared soil

Why is auxin used in weed killers?

Since auxin stimulates growth if you spray auxin onto the leaves of a plant the hormone is absorbed so this causes rapid uncontrolled growth which kills them

What are dicots?

Broad leaved plants

What are monocots?

Narrow leaved plants

Do dicots or monocots absorb more auxin?

Dicots

What is Ethene?

A gas that plants release to ripen fruits and control cell division

How is Ethene used by humans?

Added to the atmosphere so that the fruit can be rapidly ripened to the perfect stage

What are giberallins?

A plant hormone that initiates germination and the growth of stems

Give the 3 uses of giberallins

1. Used in the brewing industry to end seed dormancy by speeding up germination

2. They are used to promote flowering throughout the year

3.They are used to increase the size of fruit

What is the codon?

The triplet bases

Where does transcription take place?

In the nucleus

Where does translation take place?

In the cytoplasm

Where is adrenaline Produced?

In the adrenal gland

Where is thyroxine produced?

In the thyroid gland

Where is TSH released from?

The pituitary gland

What happens if the level of thyroxine is too high?

The release of TSH is inhibited so less thyroxine is released from the thyroid gland

What happens if the level of thyroxine is too low?

Then the release of TSH is stimulated so more thyroxine is released from the thyroid gland

What does thyroxine control?

The basic metabolic rate of your body

What does the thyroid gland use to produce thyroxine?

Iodine from your diet

What does adrenaline do?

It boosts the delivery of oxygen and glucose to your brain and muscles

What are the 6 effects of adrenaline on your body?

1. Your heart rate and breathing rate increas

2. Stored glycogen in the liver is broken down into glucose for increased respiration

3. Your pupils dilate to let in more light

4. Blood flow is diverted from the digestive system to your muscles

5. Increased blood pressure

6. Increased mental awareness

What is variation

The differences between a species

ex.height,build and colour

What are the 4 types of variation

1.Discontinuous

2.Continuous

3.Genetic

4.Enviromental

What is discontinuous variation

Where there is specific values for the characteristics

What is continuous vairation

Where the characteristic can take any value within a range

What is sexual reproduction

Where offspring are produced from 2 parents with genetic material being taken from both. The offspring produced are not identical.

What are gametes

Sex cells

What is the male sex cell

Sperm

What is the female sex cell

Ova

What happens in fertilisation to the gametes

They fuse

What happens in Asexual reproduction

Each organism produced contains identical genes which are genetically identical to the parent cell. Only 1 parent is needed.

What type of reproduction is faster → Asexual or Sexual

Asexual as it only requires 1 parent

What are Diploids

The normal body cells

How many sets of chromosomes do Diploids have

2 sets of each chromosome so have 46 in total

How many chromosomes do Haploids have

23 chromosomes

During fertilisation … …. …. …. ….

2 Haploid cells join together

What is formed when 2 haploid cells join together

A diploid cell known as a Zygote

How does the zygote produce a new organism

The zygote divides many times by the process of mitosis to produce a new organism

How are Gametes produced

A type of cell division called meiosis

What is the result of meiosis in Gametes

4 haploid cells which are produced from 1 diploid parent cell

Where does the meiosis of gametes occur in humans

In the Ovaries and Testes

What is the 1st step of Meiosis

2 copies of each chromosome is made

What is the 2nd step of Meiosis

These chromosomes line up along the middle of the cell in pairs

What is the 3rd step of Meiosis

1 member of each pair is pulled to opposite ends of the cell

What is the 4th step of Meiosis

The cell divides into 2

What is the 5th step of Meiosis

2 separate cells are formed

What is the 6th step of Meiosis

The chromosomes line up along the middle of each of the 2 new cells

What is the 7th step of Meiosis

Each chromosome is pulled in half so a single copy of each chromosome goes to opposite ends of the cell

What is the 8th step of Meiosis

Each cell then divides into 2 which results in a total of 4 haploid cells