TOPIC 1 - CELL BIOLOGY Flashcards
What do sperm cells, nerve cells, muscle cells do?
SPERM - Get the male DNA to the female DNA. It has a long tail and streamlined head to help it swim to the egg. There are a lot of mitochondria to help give it energy. It carries enzymes to digest the cell membrane of the egg.
NERVE - The function of nerve cells is to carry electric signals from one part of the body to another. They are long and have branched connections to make a network.
MUSCLE - Their function is to contract quickly. These cells are long so they have space to contract and contain lots of mitochondria.
What do root hair cells, phloem and xylem do?
ROOT HAIR CELLS - Cells on the surface of plant roots which will grow into long hairs that stick out into the soil. This gives them a large surface area for absorbing water and mineral ions from the soil
PHLOEM AND XYLEM - Phloem and xylem cells are used for phloem and xylem tubes, which are used for transporting substances like water and food. To form the tubes the cells are long and join end to end. Xylem are hollow and phloem have very few sub-cellular structures so that stuff can flow through.
Are chromosomes made of DNA or RNA?
Trick quetion;
Chromasomes are made of DNA, which is made of two strands of RNA. Chromasomes are also made of combinations of 4 amino acids: A, T, C and G
In multicellular organisms what is mitosis used for and what is meiosis used for?
Meiosis is only used for sexual reproduction, whereas mitosis is used for repairing the body, growth and, in some cases, asexual reproduction.
What is the cycle for mitosis?
- The DNA is spread out in long strings
- The number of mitochondria and ribosomes double
- It then duplicates its DNA so that there’s one copy for each cell
- The chromasomes line up at the centre of the cell and cell fibres pull them apart. The two arms of each chromasome go at each end of the cell.
- Membranes form around each set of DNA. These become the nuclei of the new cells.
- Lastly the cytoplasm and cell membrane divide.
What is the cycle for binary fission, what uses it and how is it different to mitosis?
- The circular DNA and plasmid/s replicate
- The cell gets bigger and circular DNA strands move to opposite ends of the cell
- The cytoplasm starts to divide and a new cell wall begins to form
- The cytoplasm divides and two daughter cells are produced.
It is used by prokaryotic cells.
It is different because it is A. Used but prokaryotes and B. Each daughter cell has one copy of the DNA ring but can have a variable number of plasmids. This means it can replicate quicker.
How do you work out the number of bacteria produced using the mean division time and time?
Example question:
A bacterial cell has a mean division time of 30 minutes. How many cells will one bacterial cell have produced in two and a half ho
urs?
Number of minutes / Mean division time
2.5 hours = 150 minutes
150 / 30 = 5
2^5 = 32
32 cells
What is the process in which an unspecialised cell changes to become specialised for its job?
Differentiation
What is different about adult stem cells compared to embryonic stem cells?
Adult stem cells cannot turn into any cell, for example bone marrow cells can only turn into certain cells, like red blood cells.
What is a risk of using stem cells?
That the cell may be contaminated in a lab and may make the person sicker
How can stem cells be used to preserve rare plant species?
They could take some stem cells from the plant and then make copies to increase the population.
What is the official defenition of diffusion?
DIFFUSION IS THE SPREADING OUT OF PARTICLES FROM AN AREA OF HIGHER CONCENTRATION TO AN AREA OF LOWER CONCENTRATION!
What is active transport?
The movement of a substance against a concentration gradient. This could mean taking oxygen into the blood from the alveoli even though the alveoli have a higher concentration of oxygen.
What is osmosis?
Osmosis is just diffusion for water.
What is different about a plant cell’s specialisation?
Plant cells retain the ability to differentiate through life
