Chapter 2 - Cells Flashcards
what is a cell?
the smallest unit from which all organisms are made
what are microscopes and what are they used for?
many biological structures are too small to be seen by the naked eye and so optical microscopes are used by scientists as they allow for tissues , cells and organelles to be seen and studied
cell membrane - function
it is a very thin layer of protein and fat that controls what goes in and out of the cell, it is partially permeable and separates the contente of the cell from its environment (surroundings)
cell wall - function
tough layer outside the cell membrane ; found in the cells of plants, fungi and bacteria - mainly made of cellulose, if a cell absorbs a lot of water and swells, the cell wall stops its bursting - space between fibres large molecules can go through making is fully permeable
what does the cellulose do?
forms fibres which criss-cross over one another to form a very strong covering to the cell which helps to protect and support the cell
cytoplasm - function
it’s a clear jelly that’s nearly all water, it contains many substances dissolved in it (especially protein) - metabolic reactions take place here
vacuole - function
fluid filled space inside the cell which is surrounded by its own membrane - plant cells have large permanent vacuoles that contain a solution of sugars and other substances called cell sap, animal cells have have smaller vacuoles called vesicles which also contain solutions - when the vacuole is full it presses outward on the rest of the cell and helps it keep its shape
nucleus - function
its where genetic information is stored, information is kept on the chromosome which are inherited from the organism’s parents
what are chromosomes?
a length of DNA that contains genetic information in the form of many genes, the DNA in them determine the kinds of proteins made in the cell
chloroplast - function
found in the cell of plants and contain the green colouring or pigment called chlorophyll
what is the function of the chlorophyll?
absorbs energy from sunlight that is used n making food for plants by photosynthesis- contain green starch made by photosynthesis
mitochondria - function
found in almost all plant and animal cells - where aerobic respiration takes place releasing energy from glucose for the cell to use, the more energy a cell requires then the more mitochondria it will have
ribosome - function
its where the cell makes protein, the instructions on the DNA molecules are used to link together chains of amino acids in particular sequence (where protein synthesis occurs)
what structures do bacteria cells have?
they always have cell walls that is not made of cellulose, partially permeable membrane, cytoplasm, ribosome, circle of DNA and plasmid
what are tissues?
a group of similar cells that work together to perform a particular function
what are organs?
structure made of a group of tissues working together to perform a specific function
what is a organ system?
group of organs with related functions working together to perform body functions
what is a organism?
living things performing all seven life processes
root hair cell - function and adaptation
function:
absorb water and minerals from the soil
adaptation:
<long root hair shape to fit between grains of soil so that it can reach the water
<large surface area for diffusion of water and minerals into the cell
<no chloroplasts due to it being underground
what is a specialised cell?
a cell that has developed certain characteristics in order to perform particular functions, the differences are controlled by genes in the nucleus
what is differentiation?
the process by which cells develop the structure and characteristics needed to be able to carry out their function
palisade cell - function and adaptation
function:
to carry out photosynthesis and make food (glucose) for the plant
adaptation:
>lots of chloroplast to absorb light to provide energy for photosynthesis
>tall, long shape and large surface area to maximise the absorption of light
muscle cell - function and adaptation
function:
to help the body move
adaptation:
>contains bands of protein that change shape to contract and relax the muscle
>contains lots of mitochondria to provide energy for muscle contraction
nerve cell - function and adaptation
function:
to carry nerve impulses around the body
adaptation:
>long fibres allow it to carry electrical impulses up and down the body
>branching dendrites at each end to connect to other nerves or muscles
ciliated epithelial cell - function and adaptation
function:
>to move mucus with trapped dust and microorganisms away from the lungs
>ciliated epithelium is found within the respiratory system (the trachea) and reproductive system of females (fallopian tube of uterus)
adaptation:
>tiny long hairs called cilia to help waft the mucus along the airway
>lots of mitochondria to release energy for cilia to move
red blood cell - function and adaptation
function:
to transport oxygen around the body
adaptation:
>biconcave shape increases surface area for the diffusion of oxygen
>no nucleus so that there is more room for haemoglobin which binds to the oxygen molecules
white blood cell - function and adaptation
function:
to fight pathogens which cause diseases
adaptation:
>some can change shape to squeeze out of blood vessels and engulf pathogens
>some can produce antibodies and antitoxins
sperm cell - function and adaptation
function:
to travel to and fuse with an egg cell for fertilisation
adaptation:
>long tail for movement to the egg
>lots of mitochondria to release energy to allow sperm to move it’s tail
egg cell - function and adaptation
function:
to be fertilised by the sperm cell
adaptation:
>cytoplasm contains nutrients for the developing embryo
>the membrane changes after fertilisation to stop any more sperm getting in
what equation is used to calculate magnification?
magnification = size of image
size of actual object
