Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
49 Cards in this Set
- Front
- Back
|
Where is mitochondria found and why? |
In the liver and muscles because they produce lots of energy
|
|
|
What are ribosomes responsible for?
|
Making proteins
|
|
|
What is DNA?
|
Carries the code that controls what cells are made of and what they do
|
|
|
What are chromosomes?
|
Very long molecule of tightly coiled DNA
|
|
|
What are double helix's of a DNA molecule held together by?
|
"rungs" made from bases (A +T and C+G)
|
|
|
How did Watson and Crick use other scientists data to find out about the structure of DNA?
|
- Used X-ray data showing that DNA is a double helix formed from two chains wound together
- Other data showing bases occured in pairs |
|
|
Explain DNA replication (2 points)
|
- The double helix strand "unzips" = two single strands
- Complementery base pairings attach = exact copy |
|
|
What is a gene?
|
A section of DNA that codes for a particular protein
|
|
|
Explain protein synthesis (5 points)
|
- DNA strand seperates and complimentary bases attach = mRNA
- mRNA enters ribosome (in cytoplasm) - Amino acids have 3 bases each - Amino acids join with mRNA = tRNA - Hundred of tRNA = protein |
|
|
Why can a protein have a different structure to another protein?
|
Because they have a different sequence of amino acids
|
|
|
What are the four types of protein functions?
|
1. Enzymes
2. Carrier molecules: transport smaller molecules eg. haemoglobin 3. Hormones: carry messages round the body eg. insulin 4. Structural proteins: physically strong eg. collagen |
|
|
Why are enzymes specific to their job?
|
Because the active site of the enzyme of the substrate of the job it does
|
|
|
What do enzymes do in the body?
|
Speed up reactions
|
|
|
How does a higher temperature effect enzymes?
|
At first = increases the rate (substrate particles move faster = more likely to collide)
Above 40 = active site denatures so the substrate no longer fits |
|
|
How do different pH's affect active sites of enzymes?
|
Too high or low denatures the active site
|
|
|
What does the Q10 equation tell us?
|
How the rate of reaction changes if the temperature is altered by 10 degrees
|
|
|
What is the equation for Q10?
|
Q10 = Rate at higher temp / Rate at lower temp
Eg. 2 = rate has doubled 3 = rate has tripled |
|
|
What is a mutation?
|
A change in the DNA base sequence
|
|
|
Explain why mutations affect the protein made
|
If there is a change to the DNA, the mRNA would be different so the ribosome may not be able to read it.
This means there may be a different order of amino acids/a different shape |
|
|
What 3 things cause mutations?
Give examples of each one |
1. Certain chemicals Eg. Tar
2. Exposure to radiation Eg. X-rays, gamma, UV 3. Spontaneous |
|
|
What are two harmful mutations?
|
- Occur in reproductive cells = offspring develop abnormally
- Cancer |
|
|
Give two examples of when mutations can be beneficial?
|
- New protein = improvement = survival advantage and passes on mutated DNA to offsprings
- Some have no effect |
|
|
What are multicellular organisms?
|
Living things made of many cells
|
|
|
What are 3 advantages of multicellular organisms?
|
- Can grow large
- Cells can differentiate - Organisms can become more complex |
|
|
What three specialised organ systems do multicellular organisms have to have?
|
- Communication between cells (eg nerve cells)
- System to supply cells with nutrients (eg. circulatory system) - A system to control exchanges with environment (eg. respiratory system) |
|
|
What is mitosis?
|
When a cell reproduces itself by splitting to form two identical offspring
|
|
|
What are the cells made by mitosis for?
|
Growth and repair
|
|
|
Explain the process of mitosis
|
1. Each chromosome is replicated and the DNA coils into double-armed chromosomes
2. Chromosomes line up on the equator 3. Single strands move to poles of the cell 4. Two identical cells mde |
|
|
What are the cells made by meiosis?
|
Gametes = sex cells = eggs and sperm
|
|
|
Explain the process of meiosis
|
1. DNA replicated and coils up to form double-armed chromosomes
2. Chromosomes arrange into pairs 3. The pairs divide and move to opposite poles of cell 4. Chromosome splits in half and one arm ends up in new cell |
|
|
What is a zygote?
|
When male and female gametes combine to form a diploid cell
|
|
|
What are the characteristics of the zygote controlled by?
|
The combination of genes on its chromosomes
|
|
|
Give three adaptations of sperm
|
- Small and long tails to swim to egg
- Lots of mitochondria = prove energy - Enzymes in acrosome to digest egg membrane |
|
|
What is the difference between plant and animal growth? (Size and the way they grow)
|
- Animals have a finite size and stop growing when they reach it, but plants grow continously.
- Animals grow by cell division, plants grow mainly by cell elongation but some cell division in meristems (tips of roots and shoots) |
|
|
What are stem cells?
|
Undifferentiated cells that aren't specialised for a particular job
|
|
|
Which stem cells are best?
|
Embryonic because they can become any cell needed whereas adult can only be found in certain places and can only turn into limited types of cells
|
|
|
What are stem cells used for?
|
Cure disease
Eg. blood disorders Stem cell therapy = replace damaged cells (treat paralysis) |
|
|
What are two reasons for why people agree with stem cell research?
|
Believe curing people is more important that the rights for an embryo
Fertility treatments destroy unwanted embryos so should be used to help othera |
|
|
What is a reason against stem cell research?
|
The embryo has potention for life
|
|
|
What are 3 ways to measure growth?
|
1. Measure length/height
2. Measure wet mass 3. Measure dry mass? |
|
|
What is an advantage and a disadvantage of measuring growth by length and height?
|
Adv+ Easy to measure
Dis- Doesn't tell width |
|
|
What is an advantage and a disadvantage of measuring growth by wet mass?
|
Adv+ Easy to measure
Dis- Animals heavier if eat/drink, plants heavier after rainfall |
|
|
What is an advantage and a disadvantage of measuring growth by dry mass?
|
Adv+ Not affected by water/food
Dis- Organisms have to be killed |
|
|
What are the five main phases of growth in order?
|
Infancy
Childhood Adolescence Maturity/Adulthood Old age |
|
|
When does the stage of infancy occur? What is the rate of growth?
|
First two years
Rapid growth |
|
|
When does the stage of childhood occur? What is the rate of growth?
|
Between infancy and puberty
Steady growth |
|
|
When does the stage of adolescence occur? What is the rate of growth?
|
Begins with puberty until growth complete
Rapid growth |
|
|
When does the stage of adulthood/maturity occur? What is the rate of growth?
|
Between adolescence and old age
Growth stops |
|
|
When does the stage of old age occur?
|
Between 65 and death
|
