cell division diversity and differentiation

Question 1

What is interphase?

Answer 1

The part of the cell cycle where the cell is not dividing

Question 2

What happens in G0 phase?

Answer 2

This is the resting phase where cells undergo apoptosis, senescence or differentiation

Question 3

what happens in G1 phase?

Answer 3

This is the growth phase where the organelles duplicate and the transcription of genes to make RNA occurs as well as protein synthesis of enzymes that will be needed in S phase?

Question 4

What happens in S phase?

Answer 4

This is where the DNA duplicates - housekeeping genes are duplicated first

Question 5

Why does S phase occur rapidly?

Answer 5

During replication the DNA base pairs are exposed which makes them susceptible to mutations so needs to occur fast to limit exposure.

Question 6

What happens in G2 phase?

Answer 6

Chemicals ensure the cell is ready for mitosis by stimulating proteins that will be involved in forming the spindle fibres as well as this the cell grows.

Question 7

What are the 3 things mitosis is needed for?

Answer 7

Asexual reproduction, growth and tissue repair.

Question 8

What happens in prophase?

Answer 8

The chromatins shorten and condense and the DNA supercoils. The nuclear envelope breaks down and the spindle fibres form between centrioles.

Question 9

What happens in metaphase?

Answer 9

The chromatids attach to the spindle fibres via their centromeres and are at the equator region.

Question 10

What happens in anaphase?

Answer 10

The centromere splits and the motor protein pulls the sister chromatids to opposite poles where they assume a V shape.

Question 11

What happens in telophase?

Answer 11

A new nuclear envelope forms

Question 12

What happens in cytokinesis?

Answer 12

The cell splits into 2 each with a nucleus. In animals the plasma membrane folds inwards

Question 13

What are the final products of mitosis?

Answer 13

2 genetically identical daughter cells which are clones of each other and the parent

Question 14

What is meiosis?

Answer 14

used for sexual reproduction by combining 2 pieces of genetic material via fertilisation

Question 15

What are the 8 stages of meiosis?

Answer 15

Prophase 1- chromatin condenses and DNA supercoils, nuclear envelope breaksdown and spindle forms. Chromosomes come together in homologous paris and crosing over may happen between non sister chromatids causing some allele shuffling.
Metaphase 1 - attach along the equator of the spindle fibres by their centromeres. The homologous pairs are arranged randomly facing a certain way to the pole (random assortment)
Anaphase 1 - members of each pair of homologous chromosomes are pulled apart by motor proteins. Crossed over areas separate.
Telophase 1 - 2 new nuclear envelopes form and cell divided by cytokinesis.
A short interphase occurs before that repeats.

Question 16

What are the products of meiosis?

Answer 16

4 genetically different haploid cells.

Question 17

What are erythrocytes and what adaptations do they have?

Answer 17

These are red blood cells. Have a large sa:v which means o2 can diffuse easier. no nucleus or endoplasmic reticulum plus a biconcave shape. Have a well developed cytoskeleton which makes them flexible to fit through narrow capillary walls.

Question 18

What are neutrophils?

Answer 18

They ingest invading pathogens, have a multi lobed nucleus and are attracted to the site of infection by chemotaxis.

Question 19

What are the adaptations of spermatozoa?

Answer 19

They contain many mitochondria to produce ATP
Small and thin
enzymes within the acrosome which are released once they reach the ovum to break down the protective covering
Head contains haploid male gamete nucleus

Question 20

How are palisade cells adapted for photosynthesis?

Answer 20

They have a long and cylindrical shape so pack together closely
A large vacuole so chloroplasts can be positioned near the periphery of the cell to reduce diffusion distance
Contain many chloroplasts
The cytoskeleton threads and motor proteins can move the chloroplasts

Question 21

What are tissues?

Answer 21

A group of cells that work together to perform a specific function or functions.

Question 22

What are epithelial tissues?

Answer 22

This tissue covers and lines free surfaces and has cells that are close together to form continuous sheets. Some have smooth surfaces but others have projections like cilia or microvilli

Question 23

What are connective tissues?

Answer 23

These hold structures together and provide support e.g. blood, bone and cartilage

Question 24

What are the 3 types of muscle tissues?

Answer 24

Skeletal, smooth and cardiac

Question 25

What are stem cells?

Answer 25

Undifferentiated cells which are capable of becoming any cell. Pluripotent and can express al genes

Question 26

Where can you source stem cells?

Answer 26

Embryonic stem cells from a zygote, from the umbilical cord, in developed tissues like blood and the brain