B5 Flashcards
How do embryonic stem cells develop?
They become tissues and organs in the body, that are specialised for their job
-There are 300 diferent cells by the time you are an adult
Deascribe a growing baby?
Baby takes about a week to reach the 100cell stage
after two months forms organs and is a fetus
How do plants grow?
Plants have cells called meristem cells which are unspecialised, and increase the girtha nd length and height
Why can plants grow back?
This is because meristem cells are unspecialised, meaning they can form into any type of cell, they are stem cells
Where can stem cells be found?
in animals
EG. newts and other reptiles can grow links with unspecialised stem cell throughout their lives
What can meristem cells be used for?
This allows plants to grow when cut or taken away fron the main body of the plant
the cuttind can be dipped in root powder which contains auxins, which stimulates roots to grow asthe meristem cells are stimulated to grow as roots
How do plants adapt to their environment?
Plants lean towards light when placed on windowsills, this is know as phototropism
What cells lose nuclei when it develops?
Red blood cells , lose their nucleus which is then replaced with haemoglobin, the cells develop from stem cells in the bone marrow
How does cell division work?
-It copies DNA aswell as organelles for example: ribosomes + mitochondria
What is mitosis?
Mitosis is the process where cells reproduce.
what is special about gametes?
They have half the amount of DNA as a normal cell.
What is Meosis?
Meosis is the reproduction of sex cells, which occurs in sex organs
Who formulated the modern DNA model
Francis Crick and James Watson in 1935
The rung and ladder model
What is DNA composed of?
A frame of deoxyribose and pshosphates with base pairings inbetween them
How does DNA pass on information?
Weak bond at the end of the strand unzip, leaving two single strands
- free bases then attach to the appropiate bases and two strands of DNA begin to form.
What are amino acids?
AA are combinations of three bases
this is called a triplet code
- There are 64 different types of AA
- some AA code for start and stop AA in protein chains
- Some AA have multiple triplet codes for them
How are proteins made?
Dna copies and creates mRNA
this is asingle strand of DNA with bases A,U,G,C
- mRNA is a smaller molecule that can leve the nucleus through the nuclear membranes
- Goes to ribosome, attaches to mRNA
- the ribosome reads the code and joins AA into correct order and puts AA to form proteins
Releases proteins into cytoplasm
Name three proteins in body
Keratin- makes up hair, nails and skin
strong and insoluble
Elastin- skin,
springy
Collagen
skin bone tendons ligaments
Tough inflexible
What is meant by genes switching on?
EG.
hair cells
genes switched on leads to enzymes for makin keratin to be produced
How many genes are switched on in an unspecialised cell?
ALL
What might be possible if scientists can create synthetic tissues?
Could grow organs
create humans?
Issue with giving people someone elses tissues.
The tissue may be rejected as they are made made of someones elses DNA, which can not be recognised by the body of the person receiving the organ.
What is another way of cloning?
Scientist can turn on adult cells so they can become unspecialised and then be used to grow body parts for the patient wihtout risk of rejection
Is using adult stem cells the answer?
Yes
not approved by the government despite sucessfull operations
