Cell structure and division

Question 1

what is a cell?

Answer 1

a cell is the smallest living structural and functional unit of an animals’ body

Question 2

what is the cell membrane?

Answer 2

• external boundary of the cell
• confines the cell content
• regulates entry and exit of materials
• contains a bilayer of phospholipid
• outer surface is hydrophilic
• inner surface is hydrophobic

Question 3

what is the cytoplasm?

Answer 3

• consists of cytosol which is a thick fluid
• contains cytoskeleton (made up of tubules and filaments to support and give cell shape)

Question 4

what is the nucleus?

Answer 4

• centre of the cell - controls the cell
• has perforated membrane called the nuclear envelope (Allows passage of RNA)
• contains genetic membrane in the form of DNA and RNA

Question 5

what does DNA stand for and what is it?

Answer 5

• deoxyribonucleic acid
• two polynucleotide chains that coil around eachother in a double helix carrying genetic instructions for the development, functioning, growth, and reproduction

Question 6

what does RNA stand for?

Answer 6

ribonucleic acid

Question 7

what are ribosomes?

Answer 7

• tiny granules of RNA
• synthesises proteins from amino acid using RNA
• can be in the cytoplasm or attached to the RER

Question 8

What is the smooth endoplasmic reticulum?

Answer 8

• ER
• folded membranes usually attached to the nucleus
• produce and transport lipids and steroids

Question 9

what is the rough endoplasmic reticulum?

Answer 9

• stores newly synthesised protein molecules and packages material to be secreted from the cell
• has ribosomes

Question 10

what is the golgi apparatus?

Answer 10

• processes and sorts packages and delivers proteins and lipids to the plasma membrane
• proteins move from the ER to the golgi via transport vesticles

Question 11

what are the lysosomes?

Answer 11

• secretory vesicles formed by the golgi
• contain enzymes involved in breaking down damaged organelle and dead cells
• digesting materials

Question 12

what is phagocytosis?

Answer 12

the process by which cells engulf solid particles

Question 13

what is pinocytosis?

Answer 13

the process of engulfing fluids

Question 14

what is the mitochondria?

Answer 14

• the powerhouse of the cell
• where energy is produced and stored
• outer membrane is smooth and the inner is called cristae

Question 15

what is the equation for cellular respiration?

Answer 15

glucose + oxygen = energy + water + carbon dioxide

Question 16

what is energy stored and converted into whilst in the mitochondria?

Answer 16

stored as Adenosine Tri-Phosphate and converted into Adenosine Bi-Phosphate

Question 17

what is the centrosome?

Answer 17

• found near the nucleus of the cell
• appears as cytoplasmic material and radiating microtubules

Question 18

what are centrioles?

Answer 18

a pair of rod like structures involved in cell division

Question 19

what are microfilaments?

Answer 19

• give form and shape to the cell
• form flagella
• help form cilia

Question 20

what is the cilia?

Answer 20

slender, microscopic hair like structures that extend from the surface of most mammalian cell

Question 21

what is the flagella?

Answer 21

microscopic hairs that are involved in locomotion of cells

Question 22

what are chromosomes?

Answer 22

• DNA and RNA molecules
• matching pairs are homologous pairs

Question 23

how many homologous pairs do dogs, cats, rabbits, and guinea pigs have?

Answer 23

dogs - 78
cats - 38
rabbits - 44
guinea pigs - 64

Question 24

what are autosomes?

Answer 24

non-sex chromosomes

Question 25

what are allosomes?

Answer 25

sex chromosomes

Question 26

which is smaller out of the X and Y chromosome?

Answer 26

Y

Question 27

how is a chromosome made?

Answer 27

made up of 2 identical chromatids held together at the centomere

Question 28

what are the DNA pairs?

Answer 28

adenine + thymine cytosine + guanine

Question 29

what are uprights?

Answer 29

chains of alternating sugar and phosphate units

Question 30

what are rungs?

Answer 30

formed from pairs of base attached to the sugars

Question 31

what are the two types of cell division?

Answer 31

- mitosis - meiosis

Question 32

when and where does mitosis occur?

Answer 32

continuously in growing and adult animals

Question 33

how many cells does the nucleus split into during mitosis?

Answer 33

2 identical daughter cells

Question 34

what is the process called when the cytoplasm divides?

Answer 34

cytokinesis

Question 35

what ae the 5 phases of mitosis?

Answer 35

1 - prophase 2 - metaphase 3 - anaphase 4 - telophase 5 - interphase

Question 36

mitosis: what happens during prophase?

Answer 36

- chromosomes coil up - nuclear envelope breaks down - ends when fully broken down

Question 37

mitosis: what happens during metaphase?

Answer 37

- chromosomes line up in centre of cell - spindle fibres connect to kinetochores

Question 38

mitosis: what happens during anaphase?

Answer 38

- spindle fibres contract and pull the chromatids - when they split = daughter chromosomes - ends when chromosomes reach their destination

Question 39

mitosis: what happens during telophase?

Answer 39

- nuclear membrane and nucleolus reform in daughter cells -spindle cell fibres degenerate - chromatids uncoil and lengthen

Question 40

mitosis: what happens during interphase?

Answer 40

period of rest - intense metabolic activity

Question 41

where does meiosis take place?

Answer 41

in gametes (ova/sperm)

Question 42

how many daughter cells does meiosis create?

Answer 42

4 daughter cells

Question 43

what is it called when two gametes join together?

Answer 43

zygote

Question 44

meiosis 1 : what happens during prophase 1?

Answer 44

- chromosomes thicken and coil up - nuclear envelope breaks down - chiasmata (crossover) happens

Question 45

meiosis 1: what happens during metaphase 1?

Answer 45

- chromosomes line up along centre in pairs -spindle fibres connect to kinetochores

Question 46

meiosis 1: what happens during anaphase 1?

Answer 46

- spindle fibres contract and pull the chromosomes at the centromere - one chromosome pair pulled to each line - anaphase ends when chromosomes reach their destination

Question 47

meiosis 1: what happens during telophase 1?

Answer 47

- nuclear membrane and nucleolus reformed in daughter cells - spindle fibres disappear - cytoplasm and cell divides resulting in two cells with a haploid set of paired chromosomes

Question 48

what happens in meiosis 2?

Answer 48

- 2 daughter cells divide again - 4 cells make up the gametes

Question 49

meiosis 2 : what happens during prophase?

Answer 49

- centrioles start moving to opposite poles again - happens in each daughter cell

Question 50

meiosis 2: what happens during metaphase?

Answer 50

- chromosomes line up in single file - spindle fibres attach

Question 51

meiosis 2: what happens during anaphase?

Answer 51

- sister chromatids are pulled to opposite poles of the equator

Question 52

meiosis 2: what happens during telophase?

Answer 52

- spindles break down - new nuclear membranes form and new nucleoi form around the 2 groups of chromatids - chromatids uncoil and lengthen